How the synchronization in Windows 7 Offline Files works

Hello,

In this article i will present the way offline files synchronize and focus on Windows 7 enhancements.

To understand synchronization we have to understand the concepts of “auto-caching” and “sparsely-cached” files:

- Auto-cached files are those files that are cached automatically when opened on a server configured to support “automatic caching”. Initially, only those blocks of data read by the client application are cached, producing a “sparse” file in the cache.

- Sparsely-cached files are available to the client only when the associated network share is connected (a.k.a. “online”). In order to make a sparse file available while offline, it must first be “filled” while online. Filling of a sparse file ensures the complete file is in the cache. Most sparse files are automatically filled in the background by the “CSC Agent” so sparse files are rarely an issue. However, since sparse files are unavailable while offline, it is necessary that they be filled prior to disconnecting from the network.

Optimized file synchronization:

One of the performance enhancements of Offline Files in Windows Vista is a faster synchronization process. This is achieved by using a new synchronization algorithm that does the following:

- reduces the time and bandwidth needed to identify differences between the local cache and the server

- determines which parts of a file in the local cache have changed, and then updates only those parts of the file on the network server

The process of updating only parts of a file on the server is called Bitmap Differential Transfer. It takes place during synchronization of the local cache to the server.

Bitmap Differential Transfer

- Offline Files in Windows Vista and Windows 7 uses Bitmap Differential Transfer. Bitmap Differential Transfer tracks which blocks of a file in the local cache are modified while you are working offline and then sends only those blocks to the server. In Windows XP, Offline Files copies the entire file from the local cache to the server, even if only a small part of the file was modified while offline.

Because Bitmap Differential Transfer can make the synchronization more efficient, Offline Files in Windows Vista and Windows 7 supports all file types. Offline Files in Windows XP could not synchronize large files efficiently; therefore, certain types of files were specifically excluded from the local cache.

- Bitmap Differential Transfer is not used when synchronizing changes from the server to the local cache. If a file is modified on the server when you are offline, Offline Files in Windows Vista or Windows 7 will copy the whole file to your local cache during synchronization. Bitmap Differential Transfer works only for pre-existing files and not for files that were created while working offline. Because of this limitation, files modified with applications that do not modify the file in place will not work with Bitmap Differential Transfer. For example, Microsoft® Word creates a temporary file that is used to replace the original file. These types of files are considered new, and they are copied in their entirety from the local cache to the server.

The "Synchronize all offline files before logging off " and "synchronize all offline files when logging on" are no longer available for Windows Vista and Windows 7 : https://technet.microsoft.com/en-us/library/cc749449(WS.10).aspx#BKMK_Optimized . The main reason is the client has cached the file when it has accessed to this file in read mode. Then only the difference (block of data that has changed for a file) is synchronized on a regular bases or when logon (background), logoff and Slow Link change.

What are the settings in Windows 7:

There are some settings with which you can play to ensure client are correctly synchronized before they leave the network (shutdown or logoff) :

- Configure Background Sync : this policy applies only for Windows 7and Windows Server 2008 R2 (offlinefiles.admx)

This is a machine-specific setting which applies to any user who logs onto the specified machine while this policy is in effect. This policy is in effect when a network folder is determined, as specified by the "Configure slow-link mode" policy, to be in "slow-link" mode.

For network folders in "slow-link" mode, a sync will be initiated in the background on a regular basis, according to these settings, to synchronize the files in those shares/folders between the client and server.

By default, network folders in the "slow-link" mode will be synchronized with the server every 360 minutes with the start of the sync varying between 0 and 60 additional minutes. You can override the default sync interval and variance by setting 'Sync Interval' and 'Sync Variance' values. You can also set a period of time where background sync is disabled by setting 'Blockout Start Time' and 'Blockout Duration'. To ensure that all the network folders on the machine are synchronized with the server on a regular basis, you may also set the 'Maximum Allowed Time Without A Sync'. You may also configure Background Sync for network shares that are in user selected "Work Offline" mode. This mode is in effect when a user selects the "Work Offline" button for a specific share. When selected, all configured settings will apply to shares in user selected "Work Offline" mode as well. If you disable this setting or do not configure it, the default behavior for Background Sync will apply.

This would be a short explanation on how the offline files sync works. If you have any questions, please use the comments section to ask them.

--- Jonny

Comments

• Anonymous
  January 01, 2003
  The comment has been removed

• Anonymous
  January 01, 2003
  I don't think the network drivers you mentioned (mrxsmb.sys, mrxsmb10.sys, merxsmb20.sys, Tcpip.sys) can be a problem as its writing to the offline cache on the local disk isn't it? Either way, we have SP1 installed and most other updates so they should be pretty much up to date. From your explanations (and from looking at a trace from Process Monitor) I thought when you copied to the redirected folder that is available offline it actually just copied the files to C:WindowsCSC and then uploaded them to the server in the background. So the speed should be just as fast as copying any other files from the local disk to the local disk. If not then it should at least be as fast as it would be copying to the server over the network normally surely?

• Anonymous
  January 01, 2003
  @ HELP ME: That I understand right: It is a W7 Client, the Server with the defect HDD is a Microsoft Server and you configured Folder Redirection GPO that My Docs is redirected to the Servers Share? While this Server HDD with the MyDocs of the User was in repair you worked on the Client with the Files from MyDoc, correct, they where offline available. You put the repaired drive back in the Server and you logged in at the W7 and suddenly all Files disappeared from the local Cache and the Drive on the Server? That is actually not possible, because the Client synchronizes to the Server and not vice versa. That the Files are missing on the Servers Drive after repair is expected, but after a new loggon at the W7 Client with connection to that Server, the Client recognizes that the files in the local Cache are present and not on the Server, meaning the Client starts a synchronization of the Files to the Server. Questions: did you rename the Server or the Servers Drive? (I guess it has a different drive letter now) if you logon to the W7 Client without network connection, can you access the MyDocs and do you have the Data? do you still see the mapped Network drive when loggin on the W7 Client without Network and is it still offline available? do you see any conflict messages in the SynCenter? do you see a SyncPartnership in the SyncCenter? give me your E-Mail address and I will try to help you, I then will afterwards Blog the results here, that everybody can see how we solved or not solved the Problem, Ok? Thx Jonny

• Anonymous
  January 01, 2003
  The comment has been removed

• Anonymous
  January 01, 2003
  @ all here on this Blog: It is really hard for me to help all of you with the correct solution without seeing any data's. So, most of may answers here are based on my expierience (and may daily work :)). And because of my daily work, some times my respond Time takes a while, because I am blogging in my free time, my appoligize for the delays and if I cannot help when the problem is to complex. Jonny

• Anonymous
  January 01, 2003
  @Seb technet.microsoft.com/.../cc749449(WS.10).aspx Caching When you create a shared folder on a server, there are three caching options available for that folder: Manual caching (default). If you want a file in the shared folder to be available on your computer when you are offline, you must manually select it to be made available offline. Automatic caching. When this option is selected, every time you access a file in a shared folder, the file will be made temporarily available on your computer offline. No caching. Files in the shared folder cannot be made available offline. Specific files can also be selected to be cached automatically by using the Administratively assigned offline files Group Policy setting. when you use offline files, they are available when you are not connected to the share, for example at home with no corp net access. temporary offline files are the files which are temporarely cached while working with corp net access, that saves bandwith and increases the perfomance when accessing the File a second time, because it is in your cache. When you go offline,  for example at home with no corp net access, these files are not offline available.

• Anonymous
  January 01, 2003
  The comment has been removed

• Anonymous
  January 01, 2003
  The comment has been removed

• Anonymous
  January 01, 2003
  @ Dan please also install the following patches on the W7 Clients Offline files synchronization may not finish on a computer that is running Windows 7 or Windows Server 2008 R2 support.microsoft.com/.../2561708 The Folder Redirection policy does not work if a previous user sets a redirected folder to an offline mode in Windows 7 or in Windows Server 2008 R2 support.microsoft.com/.../2610379 and this one on W7 and W2K8 R2 SP1 SMB2 directory cache is not updated correctly if a file is deleted in Windows 7 or in Windows Server 2008 R2 support.microsoft.com/.../2646563 Is the Error appearing also with the Background sync? Are you really sure the User closed the Document before he synced? Maybe the patched are helping.

• Anonymous
  January 01, 2003
  @Lionel: Nop, it is automatic switching back to online when the Bandwith (configured in the Policy) is fast enough again, the CSC will after he went offline, check every 2 Minutes if the Bandwith is back to proceed to switch to online mode. The Button "work online" is only for the Users which cannot wait 2-5 Minutes to switch back to online :). But, when the User clicks on "work offline" before the Slow Link detection puts the Cache in offline Mode, then the User has to switch back to online mode by clicking the Button manualy. to avoid to much confusion for the Users or to much User interaction need, configure the Policy to not allow the User to make changes to the Offline Files behaviour. hth Jonny

• Anonymous
  January 01, 2003
  @Leo this summary is correct, but at point 5. I use the Network Monitor and the Sync Log. For the Problem that Auto-Cached  files are not always got deleted, Hm, sorry but try the KB Article: Temporary files do not synchronize correctly to a non-DFS share on a server from a client computer that is running Windows 7 or Windows Server 2008 R2 support.microsoft.com/.../2434932 and I recommend the KBArticle: The Folder Redirection policy does not work if a previous user sets a redirected folder to an offline mode in Windows 7 or in Windows Server 2008 R2 support.microsoft.com/.../2610379

• Anonymous
  January 01, 2003
  @Chris: In your case pls. make sure you have the SP1 and the latest CSC Binarys installed. Also, make sure the AV is not scanning mapped Drives. If you configured in addition Folder Redirection, install the 2nd Fix as well. Offline files synchronization may not finish on a computer that is running Windows 7 or Windows Server 2008 R2 _support.microsoft.com/.../2561708 The Folder Redirection policy does not work if a previous user sets a redirected folder to an offline mode in Windows 7 or in Windows Server 2008 R2 _support.microsoft.com/.../2610379 this should helb with the Performance Issue. Also I recomend you to update all Network Related Drivers, like mrxsmb, mrxsmb20, mrxsmb10, rdbss...... and so on. If the File Server is a Windows Server 2008 R2, ok, if it is a non Microsoft Server check if that one is SMBv2 capable. If you are still using SMBv1, make sure Oplocks are enabled on that Server. Hth Jonny

• Anonymous
  January 01, 2003
  The comment has been removed

• Anonymous
  January 01, 2003
  Hi Jim, In XP all Files which are in sync with the Server are in the Local Cache, if you do not migrate the Files to W7 and the System is up,a Full Sync will occure to fill the Local Cache. Impact depends of the amount of Data in the Users Folder which are synched. If you have a slow WAN Link, I would suggest to migrate the Data. HTH Jonny

• Anonymous
  January 01, 2003
  Hey George, don't force the clients to work offline. You dont need to configure the Background sync, it is done automaticaly. When you redirect the Desktop and the myDocs, they will be offline available automaticaly. When you loose the connection to the Server the User will work in the Cache automaticaly, when the Server comes back online a Backgrund sync will be triggert by the System. Even though the Client is online, the User will first work in the local Cache and the system will sync the changes to the Server. Hint: about your Server 2008 SP1 => SP1 is not supported by Microsoft anymore, you should install SP2 or did you mean R2 SP1?

• Anonymous
  January 01, 2003
  Afternoon Jonny, There is a lot of good information here, but i wonder if you're able to assist with my dilemma?  

• Trialing Offline Files on Windows 7 SP1 Laptops.  
• Every laptop has one user who has a (DFS) Home Drive mapped as H.
• Files are archived off the DFS after x period of inactivity.
• Offline Files is setup to Sync the Home Drive. Now l have no problems with the sync process as such.  My issue is that file placeholders on the DFS that have been archived are being recalled due to the W7's Offline File Sync?  I this a limitation? Or am l missing something? Any help would be appreciated. Ben

• Anonymous
  January 01, 2003
  On client computers running Windows 7 or Windows Server 2008 R2, a shared folder automatically transitions to the slow-link mode if the round-trip latency of the network is greater than 80 milliseconds, to avoid this you can use the GPO "Slow Link Mode" and configure it to disabled. For troubleshooting use Network Monitor and take a Trace to find out if Client or Server is causing this issue. Also you should see a Event in the Sync Log which tells you the Latency when transitioning the share to offline. regarding the IPv6: when the scope is offline, the CSC service attempts an “automatic reconnection attempt” by communicating with the server, every 2 minutes! Removing IPv6 reduces the number of network transport arrival messages which occur, which reduces the number of “demand” reconnection attempts that are made.  This would make it more likely to have to wait the full 2 minutes until transition to online. HTH Jonny

• Anonymous
  January 01, 2003
  Hi cak, first of all I recommend besides SP1 for the W7 Client, to install the latest Binary's for CSC. support.microsoft.com/.../en-US Cscsvc Feb. 2012 support.microsoft.com/.../en-US Csc.sys Jan 2012 To answer your questions: [1] I am not sure, never tried it, but I dont think this will bring back your Data. System Restore just puts the System in a last good known state. [2] the Backup should be done on the Server, a synch on a regulary base is recommended. Sorry, hth Jonny

• Anonymous
  January 01, 2003
  @Patrik: Partial Sync sounds like you have an orphant sync Partner. Check in the SyncCenter if there is a Sync Partner which is not valid anymore and delete it. If this is not the case my best gess is Cache corruption. In this case, save the files from the Cache to another Location, install SP1 (I always recommend this :)) and the following KB You may encounter file corruption issues when you use the Offline Files feature to synchronize data in Windows 7 _support.microsoft.com/.../2523887 Set in the Registry the following DWORD: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesCscParameters FormatDataBase Value=1 Reboot the Client / that should do the Trick. Hth Jonny

• Anonymous
  January 01, 2003
  I'm tempted to, but I hate ringing them because it could potentially cost £250, but also because from the large number of people complaining about Offline Files in Windows 7 on the internet along with all of the issues that we have found, it seems like its probably not worth spending much more time and effort on it. We keep having more and more isues, such as: sync failing randomly with Access Denied messages even though permissions are all fine and it will work the next day for the same user without us changing any permissions, conflicts not clearing even after the user has marked them as ignored, sync saying it has completed successfully but then when the user goes offline half their files aren't available, the "work offline" button seems to never actually just work (always complains that files are open even when absolutely nothing else is open on the machine), files still showing in the offline version of the folder when they have been deleted from the server even after a full successful sync, access denied errors for syncs that were setup on other user's profiles (come on, this was an issue back in the XP days, surely it should have been fixed by now)... I could go on, but at this point its safe to say that we are getting pretty fed up with it and looking for an alternate solution.

• Anonymous
  January 01, 2003
  The comment has been removed

• Anonymous
  January 01, 2003
  Thanks for the article and for responding to the comments - answered some questions I had. I have to say though, we have had nothing but problems with offline files in Windows 7 so far :( the latest issue we've discovered is that copying files to any share that is made available offline is extremely slow (10% of the speed we get if we don't make that share available offline and copy the exact same files). Any ideas why this would be? Shouldn't it be faster if anything if its actually writing them to C:WindowsCSC and then syncing them with the server in the background afterwards? Thanks Chris

• Anonymous
  January 01, 2003
  The comment has been removed

• Anonymous
  January 01, 2003
  @David: It is not because of the Path, problem in the Cache => Solution=SP1 for W7 Sorry :( hth Jonny

• Anonymous
  January 01, 2003
  the Server Side option to enable caching on the Share does allow the Client to have it offline when he chooses to do so with the Client side setting "always available offline". If the Client chooses "always available offline" on a Share which has the setting caching disabled on Server side, the offline Files Feature on that share will fail. hth Jonny

• Anonymous
  January 01, 2003
  @Chris If the problem is really big, with impact on most of users open a support case with Microsoft. This will be the fastest way to solve your problem.

• Anonymous
  January 01, 2003
  @JM use the GPO: "Configure Background Sync : this policy applies only for Windows 7and Windows Server 2008 R2 "

• Anonymous
  January 01, 2003
  Thanks for the response. I've installed the hotfixes you mentioned on one of our 64 bit machines but still no change I'm afraid. The server we are copying to is Server 2008, but like I said copying to the server on a share that is not "available offline" is fast, its only copying to a share that is available offline that goes incredibly slowly (the test I just did went at less than 1 Mbps, copying the same files to another share on the same server went at 9 Mbps). I will see if we can add C:WindowsCSC to the exceptions list in our AV software though and see if this helps

• Anonymous
  January 01, 2003
  Hi Rajan, if you modify a Word Document while offline, then you will synchronize it to the Server when you are online again. I wrote: ....changes from the server to the local cache..., that means, if you Modify the Word Document on the Server and it will then be synchronized to your Client, Bitmap Differential Transfer is not used. This is valid for all files in the cache... I used Word just for example For troubleshoooting you can use the Network Monitor.

• Anonymous
  January 01, 2003
  I will need more Informations, like: conflict message ? Transparent Caching activated? File Server has Oplocks enabled? How do you synchronize, manually or Background synch? where do you see the conflicts, Synch Cenetr or Synch Log?

• Anonymous
  January 01, 2003
  Hello inspirion12, we do a full sync, you can avoid this by configuring the GPO: Policy: Turn on economical application of administratively assigned Offline Files Category Path: Computer ConfigurationAdministrative TemplatesNetworkOffline Files Supported On: At least Microsoft Windows Vista This policy setting allows you to turn on economical application of administratively assigned Offline Files. If you enable this policy setting, only new files and folders in administratively assigned folders are synchronized at logon. Files and folders that are already available offline are skipped and are synchronized later. If you disable or do not configure this policy setting, all administratively assigned folders are synchronized at logon. hth Jonny

• Anonymous
  January 01, 2003
  Have a question regarding log on sync.. does it do a full sync? or just quick sync like windows xp?

• Anonymous
  January 01, 2003
  @ Michael.S.: sorry for the huge delay and hopefully you still need this Info: When you save files to the redirected Folder My Docs., you will always save them in the local cache first. The Background sync will sync it to the Server. A Fullsync is allways done when the User Logs off or on to the W7 Client. hth Jonny

• Anonymous
  January 01, 2003
  @Leo: You can set the value in the GPO to 0 but it is not supported, we recomend a minimum of 1. In your case, sorry your Network is to fast :), I wish I had a Net like this. But, your Scenario is actually what Auto Caching does, after Logoff or shutdown the Cache is empty again. One Point I did not understand from what you want to do, "you have my Documents redirected to a Server share.... like to configure workstations to cache ...." On this my answer is, when you Redirect My Documents to a File Server, those Files are automaticaly made available offline, meaning in the Cache. The Folder Redirection is activating the Offline Files Cache automaticaly and stores the Data there. Hth Jonny

• Anonymous
  April 14, 2010
  The comment has been removed

• Anonymous
  May 25, 2010
  Hello full sync is only at login, or when you schedule it. The same for User B. But your description sounds like that User A & B are using the same share in offline files Feature!? I dont recommend this. better to have a own share for each user. If you want to share the same Documents for every User, then you should use Microsoft Sharepoint. hth/brgds Jonny

• Anonymous
  June 17, 2010
  Thanks for the write-up, Jonny.  I've got a related question.  How would I go about setting a policy that would force synchronization on a schedule (every 5 minutes) for all laptops on a domain?  Is that possible? Thanks.

• Anonymous
  June 17, 2010
  Apologies:  Would be policy on a Vista/Windows 7 domain.

• Anonymous
  June 30, 2010
  Can you explain the concept of Temporary Offline Files vs Offline Files ? Not sure to fully understand the use of this functionnality.

• Anonymous
  November 17, 2010
  hello, i have some problem with synchronize in windows 7, prior to  windows 7 this problem is never exist, i used folder redirection to NAS for document desktop and profiles for all users, and we use a mobile concept here, so one computer isnt belong to one user, sometimes the files not synchronized at all, i notice that there are a conflict appears in sync center, so the user need to login on the last computer where they modified the files first, and then they need to resolve the conflict and the synchronize will be ok, i think this is happened because the files is saved in local cache and not sync with the NAS, i assume this because see in my backup system (Symantec Exec 2010), somefiles that backed up isn't up-to-date. this never happen on xp, because the sync always occur when logging on/off i think this can be solved by background sync, could you give me a recommended setting for this fyi : DC : server 2008, NAS : storage 2003 and sorry for my bad english thanks

• Anonymous
  November 28, 2010
  i've already checked the comment for the conflict, it said "a file was change in this computer and the server when this computer was offline", referring that statement, i want to redirection user's document folder without offline files feature. i just set new folder redirection policy with disable rules for : "prevent use of oflline files", "remove make available offline", "prohibit user configuration of offline files", and "action on server disconnect" is set to "never go offline" with policies above i want to make a folder redirection act like a normal mapped network drive, but there are still conflicts for the users who use this policy, or i need to set in slow-link mode too? thanks, br

• Anonymous
  November 30, 2010
  The comment has been removed

• Anonymous
  January 11, 2011
  The comment has been removed

• Anonymous
  January 26, 2011
  Jonny, you seem to really know your stuff on this so let me throw this scenario at you. When saving a file to a redirected folder thats been synched (My documents) on windows 7, is there any way to configure sync center to save the file to the offline folder first and then upload to the server location as network permits. I wanted to cut down on the overhead involved with redirection without putting things in an offline state as we require real time updating from server to client. Thank you in advance.

• Anonymous
  February 24, 2011
  Hi, Short question regarding the usage of offline (slow-link) and online... I have redirected folders and I put some rule to change to offline mode where the latency is more than 80 ms. Everything works, but the question is the reverts back to online mode? As I read it's not automatic, the user should click on the Online button to enable it again... Right? It's strange and not usefull. For people that is traveling a lot, they should be in slow-link on external site, but in online when they come back. Any comments? Thanks you

• Anonymous
  April 20, 2011
  I'm seeing problems with machines using offline files when more than one user has logged on.  Any advice?  We all have our own private home folders on a common share, eg \servershare<username> and we re-direct Documents (W7, 64 bit) directly to our home folder. When another user has been on the computer we're getting errors syncing for the original user (UserA).  They say access denied for UserB (\servershare). Is it because the share path is common?

• Anonymous
  June 22, 2011
  a client Workstation linked the 'my documents folder' to a user share on the server and was setup to work offline... Unfortunately the user share drive became faulty and was sent for repairs....Whilst this was happening, we could use all files in the MYDOCS folder (i guess offline). The drive was sent back after repair (it was like brand new) and when we put it back into the server 2 weeks later, all of the offline files on the computer disappeared. Please help me find files!!! i have looked at csc folder but with no luck tracing my missed files!

• Anonymous
  August 24, 2011
  Hey Jonny, I got over your link. We are about to deploy offline files with our folder redirection for desktops as it wasnt enabled before. I want a way to make sure if our file server goes down users can access their my docs and desktop. Now questions: I was thinking to force all desktop to work offline and every 15 minutes to do a background sync to the server and send a copy of the files there as well. What do you think about that ? We are all windows 7 and 2008 SP1 file server.  Whats the best practice for desktops sync etc. Should users on desktops work online or offline ? I would prefer to have them offline because our file server speed is not that fast and also if it crashes users will still have everything on their desktops... let me know thanks a lot.

• Anonymous
  August 26, 2011
  No I really meant SP1 will get SP2 install as well. We had folder redirect implemented for a long time but with disabled offline files.. from the previous network admin. So I decided its best for us to have sync and offline files. Was not sure if its better for users to work online all the time or offline .. what`s the best practice so far we got these settings:

1. Configure Background Sync ------------- Enabled -Sync Interval 13 minute -Sync Variance 2 minute -Enable Background Sync for shares in user selected "Work Offline" mode
2. Limit disk space used by offline files ---------Enabled -Total size of offline files 35000 MB -Size of auto-cached files 1000 MB
3. Allow or Disallow use of the Offline Files feature ---------Enabled
4. Remove "Make Available Offline" -----------Enabled
5. Configure slow-link mode -----------Enabled -Throughput=10000bits Latency=10ms for round trip ping

• Anonymous
  August 26, 2011
  I looked again and we do gave SP2 :) So the reason was to have that Background Sync so often so that if a user modifies a file while working offline and then he goes into another computer to actually have that file available to him. Users dont understand how sync really works..  But if the desktops work online that wont be an issue anymore.... The reason I wanted to force all desktop to work offline was because our file server was slow... ISCSI slow san... etc...  and though user experience would be a lot better on their local hard drive...

• Anonymous
  September 09, 2011
  Hi, I have a huge problem and have been looking all over to find an answer, hopefully you can help me. Judging from earlier answers here, you seem to have the knowledge needed, Jonny. We changed server computer yesterday and all "home" folders of all users in the domain was copied from the old server to the new one. It was then discovered that my home directory, H: (My Documents synchronized with a user directory on the server) contained a lot of tmp files (instead of Excel, pdf etc files), actually the number of tmp files was a lot more than the number of original files. The reason for this seem to be that my synchronization has not worked for some time (appr. a week or a bit longer). What was done on my computer was the the user account was changed, a new profile was created. Since my sync with the server has not worked, my data was only available on my previous profile. We also changed domain name. Is there some way I can get access to what was my offline files for my previous profile? Hope I have explained good enough. I read the question from John Hagan above and it seem to be a similiar problem, but it was never made clear if he ever got the missing files back. And I have also the dimension with the change of profile. Best regards Daniel

• Anonymous
  September 18, 2011
  Hi again, Problem was solved by recreating the old profile and then the old files could be accessed again and copied to the server. BR /Daniel

• Anonymous
  November 30, 2011
  Any tips about solving synchronization issues with guid.tmp files created by Office applications (PowerPoint and Word). We haven't been able to find a permanent solution to this yet. Thanks.

• Anonymous
  December 16, 2011
  I’m running into an Offline Files slow detection issue where slow link latency is within our threshold, but “bandwidth” = 0. Is there a way to troubleshoot this? I’ve tried enabling Event Viewer / OfflineFiles (Debug & SyncLog) but no useful clues on root cause. With XP, enabling verbose userenv logging was very helpful, but that ability has been limited with Windows 7. Side question – IPV6 is not enabled on our networks and our machines, would this have any impact on this issue? Thanks!

• Anonymous
  January 16, 2012
  The comment has been removed

• Anonymous
  January 26, 2012
  Great blog post! What means partial sync in Windows 7? We have an user getting in Sync center error message about partial sync and we couldn't find a good explanation for Windows 7 (server is WS2008R2 SP1) Kind Regards, Patrik.

• Anonymous
  January 26, 2012
  Thank You!!! We will try your recommendations. Best regards, Patrik T.

• Anonymous
  January 26, 2012
  Hi, this is Dan. Thank you for your previous answer regarding my question about Office .tmp files. We had a quiet short period without sync errors, but now they are back again. Here are the answers to your previous questions: We are running Windows Server 2008 R2 with SP1 and Windows 7 Ultimate x64 with SP1. All the available patches from Microsoft Update are installed. We didn’t deploy any GPOs to tweak the Offline Files or network settings, only default setup. Trend Micro WFBS is installed on the server. Clients use MSE as antivirus solution. conflict message ? In Sync Center the error message states: “Access is denied” and the files with sync errors are .docx or .tmp that this user or another user was working on. Transparent Caching activated? Not activated. Well, it is just default setting for WS2008R2, which I believe is not enabled by default. File Server has Oplocks enabled? How do you synchronize, manually or Background synch? We click on Sync All in Sync Center. where do you see the conflicts, Synch Cenetr or Synch Log? We see the conflicts in the Sync Center. Thank you for the excellent blog and taking care of our comments. We appreciate any tips from you. /Dan

• Anonymous
  February 02, 2012
  Hi Jonny,  Thank you very much for the article itself and for answering questions. Could you clarify caching of server share files on the client workstation side? In our environment we don’t need Offline Files, but Client Side Caching technology (judging from its name) would be very useful.  There is a computer lab. 40 Windows 7 SP1 workstations in AD domain (forest & domain functional level - Windows Server 2008). Each student has a home folder on a Windows 2008 R2 file server. "My Documents" and other personal folders are redirected inside the home folder, so all students’ files are on the server. Most files are big - 100 Mb is common, some files are more than 500 Mb (students are architects; these are CAD, photo panoramas, and video files). Network is a stable 1 Gb Ethernet LAN.  We'd like to configure workstations to cache a file locally when an application opens it from the server (it is close to your description of "Auto-caching"). It will significantly reduce read/seek time of future file operations. The best strategy would be to keep the file in the local cache till the end of the user session and clean it up on logout.  Does Windows implement this or similar strategy? Can "Transparent caching" be of help here? The latency time in the network is less than 1 ms. But in GPO we can set network latency for transparent caching to 0. How does "Transparent caching" work in this case? Best Regards, Leo

• Anonymous
  February 03, 2012
  Hi Jonny,  Thank you very much for your answer.  According to it, files from redirected folder are going to Offline cache automatically. There are three problems here.  Could you comment them?

1. We don’t want to cache the full content of student’s redirected folders. What we really need is caching of files by requests (Auto-Caching).  There are two main reasons for that: a student has up to 15 Gb of data in redirected folders; student is not bounded to a workstation, so each logon to another workstation will cause a full synchronization. So, if Folder Redirection automatically enables Offline files with full synchronization, we’d like to avoid it. Is this possible?
2. I can’t see “automatic” caching of redirected folders or can’t understand what you mean by “automatically available offline”. As I remember, in Windows 7 Offline files are enabled by default. So, if a connected share is marked for caching then it always will go to Offline Cache. Am I right? In this case “automatically available offline” means just that Windows treats redirected folders as connected shares. Do I understand correct? I am asking because if I set Offline Files to “Disabled” I see no caching any case, despite Folder Redirection.
3. According to description of “Transparent Caching” it is based on the same background technology as “Offline Files”, but it doesn’t rely on “Offline Files” itself. Is this correct? If latency time about 100 ms what settings will activate Transparent caching of files WITHOUT activating Offline Caching with unavoidable full synchronization? And the last question here. I use ProcMon utility from SysInternals Suit for monitoring caching process. When Offline Files is enabled I can see read/write activity in subfolders of “C:WindowsCSC2.0.6”. Windows creates copies of network files and uses them. I suppose to see the an activity in the same folder in case of “Auto-Caching”. Or “Auto-Caching” doesn’t use Client Side Cache? Best Regards, Leo

• Anonymous
  February 06, 2012
  Hi Jonny,  I figured out most answers just thinking about my questions and your answers over the weekend.  Thank you.  Still can’t understand cache management policy – according to my tests cached files never get out of the cache during a user session even if cache limit is reached. If my conclusion is correct, I am afraid it can make serious problems on the client side. Above that I see that Auto-Cached  files are not always got deleted during logout/reboot. For some domain accounts cached copies remain in the cache. I will make several tests to identify which particular account parameter determines this difference and ask you more precisely later. Regarding questions from my previous post. I understood that:

1. Offline Files, Auto-Cache, Transparency cache work only if Offline Files are enabled on the Client side .
2. I didn’t recognize the border between Offline Files and Auto-Cache as I didn’t take automatic offline availability of redirected folders into account. So, to make a share available offline we need to set it manually (locally or through Group Policy) or use folder redirection (as redirected folders are included in the list of offline folders by default).
3. Of course, we can disable automatic availability offline feature for Redirected Folders through Group Policy.
4. In our environment we don’t need Transparent caching as Auto-Caching does exactly what we need. So, we should enable Offline Caching, disable Offline availability of Redirected Folders, and set “All files and programs that users open from the share will be automatically available offline” cache policy for shares which we want to cache.
5. Offline Files, Auto-Cache, Transparency cache utilize the same background technology. Files are always saved into subdirectories of WindowsCSC folder. Process Monitor utility is a proper tool for monitoring the background process of caching. Thanks again. You see – your answers are really helpful. Best Regards, Leo

• Anonymous
  February 07, 2012
  Hi Jonny,  Thank you for the reply. I will give NetMon a try as a CSC monitoring tool, thank you for the recommendation. I use Event LogApplication and Service LoggingMicrosoftWindowsOfflineFilesSyncLog as a source of information on cache synchronization, but Process Monitor gives me a feeling of looking into internal world of CSC :) Unfortunately, articles that you mentioned seem unrelated to our case (judging from their scenario descriptions). If you recommend to install these hotfixes anyway, I’ll follow your advice. I performed several tests and came to a conclusion that the difference between user accounts with different behavior is in "Delete cached copies of roaming profiles" Group Policy. If an account has a roaming profile and "Delete cached copies of roaming profiles" Group Policy is Enabled then Auto-Cached files are cleaned up during logoff as well as the profile itself. If "Delete cached copies of roaming profiles" Group Policy is not configured or the user doesn't have a roaming profile then Auto-Cached files remain in the Cache during logoff (and the profile itself remains in the C:Users). Group Policy "At logoff, delete local copy of user’s offline files" is always enabled with “Delete only the temporary offline files” setting on. Our environment: Stable gigabit LAN; AD domain (forest & domain functional level - Windows Server 2008); Windows 2008 R2 x64 Standard SP1 file server; Windows 7 x64 Professional SP1 client workstations Related Group Policy setting (all are defined in Computer part of Group Policy):   Most user’s folders are redirected into subfolders of home folders (all home folders are in a file server share. This share has “All files and programs that users open from the shared folder are automatically available offline” with “Optimize for performance” caching policy. Access-based enumeration is enabled. )   - Allow or Disallow use of the Offline Files feature – Enabled   - At logoff, delete local copy of user’s offline files - Enabled with “Delete only the temporary offline files” setting on   - Configure slow-link mode – Disabled   - Limit disk space used by offline files – Enabled.  30,000 Mb   - Do not automatically make redirected folders available offline – Enabled   - Prohibit user configuration of Offline Files - Enabled During the tests I saw that all cached files were temporary files - the overall size of cached files was always equal to the size of temporary files. When I manually deleted temporary files, the reported size of offline files came back to 0. I tried to set “Delete only the temporary offline files” off, but it didn't make any difference. It looks like Auto-Cached files of a user remain on the computer till the profile of the user remains there. Even reboot doesn't clean up Offline Cache full of temporary files. I am afraid it can lead to uncontrolled growing of Offline Cache if number of users with locally stored profiles is big. To my mind, it can't be "by design" behavior. Do you have any ideas/suggestions regarding the case? I appreciate any tips from you. Best Regards, Leo

• Anonymous
  April 19, 2012
  The comment has been removed

• Anonymous
  April 30, 2012
  Hi Jonny, There is not a lot of detailed information about Offline Files, so I'm happy to see you answering some of these posts.  I'm hoping you can help me figure out what is going on in one office.  Windows 7 Pro workstations, Windows 2008 Server.  Their previous IT person had offline files enabled, I'm assuming for network stability in case of server outages.   Anyway, I had one user who could not save a Word doc he had opened on a network share (which offline files were enabled for).  I checked it and saw that the file was marked offline,as were several other files.  The parent folders were online, but several word docs and other files were offline.  I looked at sync center, and noticed there were some outstanding conflicts.  I resolved the conflicts (about 4 total, by keeping both copies of two word files, and deleting 2 tmp files that were) and the sync completed successfully.  When I returned to the folders, the files that were previously offline were now missing.  I checked the offline files cache and they were gone from there as well.  I can't understand how that could happen. I ran a file recovery program but could not find a trace of them.  The user is extremely unhappy.  Since the files were created in offline mode, they never made it to the server, and hence into the backups.   A couple of questions: (1) I've seen some references to System Restore and whether or not that restores the CSC folder.  Does it?  It's my only hope of retrieving these files, I think.  I see a restore from before the sync, if I were to restore, would the offline files cached also be restored as of the restore date?   (2) Is there a way to backup the offline folders cache? Thanks!

• Anonymous
  May 17, 2012
  The comment has been removed

• Anonymous
  May 25, 2012
  Jonny, I am facing a global XP to 7 migration. Some locations don't have great WAN links. I want to minimize the amount of data that I migrate from XP to 7, but I need to balance that with minimizing the amount of data copied across the WAN once the new Windows 7 system is up. My questions are: In XP, if offline files are in sync with server, what kind of data resides in the Cache folder? (e.g. most recently used only?) in XP, if offline files are in sync with server, do we need to migrte Cache folder data? If offline files are in sync with server and we do not migrate the cache folder what will happen when user login to Windows 7 system first time? In short, what will the network impact be if we don't migrate the CSC from XP to 7? I know that USMT won't migrate the CSC by default, and I know how to turn it on. But I need to justify turning it on before I do it. Any help will be appreciated. --Jim

• Anonymous
  June 15, 2012
  The comment has been removed

• Anonymous
  September 07, 2012
  Hi Jonny, Great information that is nowhere else to be found. Lets say that microsofts information on offline files is sparse :) After reading your post on the topic i have some questions i hope you will be able to answer for me. Offline files can be a little confusing to understand especially because it can be configured both on the share level on a file server and also on the client computer. Here are the questions: On a share's advanced properties under the caching tab, you can enable the feature by ticking "all files and programs that users open from the share are automatically available offline". This description seems not to be true. I have made a test where i created a new empty share and mapped that on a windows 7 client computer. Then i poored in a bunch of files to the share, but from the file server. Meaning that the client computer did not create those, neither open them. But it seems that these files are still being cached in the background, meaning each file is slowly cached and gets the state of "available". Is it therefore not a wrong description to give the above enabled feature? SO if it is the case that all files are synchronized, being opened by the client or not, what is the difference between enabling caching on the share (SERVER SIDE) and ticking the "always available offline" feature in the "offline files" tab under properties of the mapped network drive (CLIENT SIDE)?

• Anonymous
  December 05, 2013
  Hi Jonny, Thank you for a wonderful post.  For simplicity, let's say I'm using redirected folders for My Pictures only.  I want to know where a picture is read from if a user opens it with and without Transparent Caching enabled.  I have the default of "always available offline" enabled.

1. Without transparent caching, the file is read from network share as I understand, even if the file is "fully cached" on the client's machine?
2. Is there a way to force the reads to come from the client's cache without transparent caching?
3. With transparent caching turned on, the files are obviously cached when opened, but are these "transparently cached" cache files different from the cache of regular offline files? To me it seems like transparent caching should not exist but its behavior just on be default.  If I have a local copy of a file, why not always use it if it's up to date? Secondly, I am wondering the behavior when someone logs onto a machine for the first time that already has data on the shared server drive.  Is data slowly transferred from the network drive to that machine's local cache?  With our techs who log into many computers I don't want to have long login times but do want the files to be available offline for the tech's home machines.

• Anonymous
  January 08, 2014
  WIN7/GPO: Offline Files, Transparent Caching
• Anonymous
  January 24, 2014
  So what would you advise doing for a mix of laptops and desktops, where the laptops may work remotely with VPN access to the servers? just enable "configure slow link mode" and use the default values so if their VPN connection is that slow it will drop into offline mode by default?
• Anonymous
  December 10, 2014
  everywhere I read it says use Sync Center to manually sync folders. But I can't find a way in the Sync Center to make it manually sync. There is no button that's says "Sync Manually" or anything like that.
• Anonymous
  January 06, 2015
  Dear i am using windows 2003 server as network storage.My windows 7 client could not sync offline files to network storage after the server become online after disconnect.All offline files are cashed locally.I want to implement a GPO.Please guide.
  
• Anonymous
  February 05, 2015
  Please can anyone tell me if it is possible to set the Slow Link detection checking interval to reduce it from it's default (2 minutes?) as I find it takes too long for a machine to detect that it has transitioned from a slow link to being on a fast link and hence make all the files on the network again rather than just those that are cached in a loadpoint?
  
• Anonymous
  April 09, 2015
  I currently have a client that uses offline folders to sync thier home drives with sizes ranging from 20MB to several GB. Multiple users have been experiencing an issue where they cannot save a file that is located on their synced home drive as "it is in use by another person or process".
  
  My first thought was that the Sync Centre is trying to sync the files whilst the users are working on them, giving the error. Usually, deleting the stored cache and forcing a re-sync works but i've got a couple of users that this has not worked on. Its not a permissions issue, as the users have full control of their folders.
  
  Attempted fixes / information:
  
  1. Have checked Group Policy and there are no restrictions on Offline Files, synchronisation or slow connections
  2. Users have full permissions to their files. Owners are the domain administrators
  3. Offline files are NOT encrypted - Bitlocker full disk encryption is in effect
  4. Network connection >10MB/s - no known network bottlenecks
  
  One theory I have been working on is the amount of space on the server may be an issue - 8% free space (32GB). Could this be causing issues with respect to paging files whilst users home drives are syncing?
  
  Any assistance would be greatly appreciated.