Auto-expanding archive question

Kenny Stern 371 Reputation points
2020-11-05T16:13:34.967+00:00

In the process of migrating to Exchange online. We are first migrating our Enterprise Vault archives to the online archive and then plan to migrate primary mailboxes. We've enabled auto-expanding archives in Exchange online but they are not expanding, which is causing issues with EV migrations that are over 100 GB.
Is this because the primary mailbox is still on-prem? Do auto-expanding archives not expand if the primary mailbox is still on-prem?
Thanks

Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
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  1. Andy David - MVP 144.4K Reputation points MVP
    2020-11-05T16:19:59.897+00:00

    Well, the biggest thing is that the expanding archives are limited to only expand 1GB per day. If you attempting to copy a mass amount of email, it doesnt work that way

    https://video2.skills-academy.com/en-us/microsoft-365/compliance/unlimited-archiving?view=o365-worldwide

    Auto-expanding archive is only supported for mailboxes used for individual users (or shared mailboxes) with a growth rate that doesn't exceed 1 GB per day. A user's archive mailbox is intended for just that user. Using journaling, transport rules, or auto-forwarding rules to copy messages to an archive mailbox is not permitted. Microsoft reserves the right to deny unlimited archiving in instances where a user's archive mailbox is used to store archive data for other users or in other cases of the inappropriate use.

    Additionally, expansion is not in real time:
    Why do I need to wait 30 days for expansion to take place?
    This question comes up a lot and can be confusing, but technically, archives are expanded as soon as the managed folder assistant is able to successfully run on the main archive that has reached the transition size (90GB). The 30-day period is the retention period for data that has been moved from the main archive to the auxiliary archive. We call this data ghosted content within the archive mailbox location and we keep a copy for 30 days to provide us (and you) with a safety net in the service in case we run into any issues during the data move from main archive to the auxiliary archive. After that period expires we flush the data in the main archive to release the space.
    Will the archive immediately expand when it reaches the threshold?
    Expansion does not occur in real-time, in other words we only check if a mailbox should be expanded when managed folder assistant runs on the main archive. Managed folder assistant is expected to process the mailbox successfully within 7 days (it might be sooner depending on service load) or

    https://techcommunity.microsoft.com/t5/exchange-team-blog/office-365-auto-expanding-archives-faq/ba-p/607784

    Note the license requirements as well

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  1. Lydia Zhou - MSFT 2,371 Reputation points Microsoft Employee
    2020-11-06T05:58:25.4+00:00

    @Kenny Stern

    Agree with AndyDavid. The additional archive storage space won't be used for this scenario. We suggest to move a part of archiving items to pst files to make sure the archived mailbox can be moved to and work normally in Exchange Online.

    For your reference: How to Migrate Archive Mailboxes Over 100GB to Exchange Online.
    Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

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