Back up using Azure Application Consistent Snapshot tool

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This article provides a guide for running the backup command of the Azure Application Consistent Snapshot tool that you can use with Azure NetApp Files.

Introduction

A storage snapshot based backup is run using the azacsnap -c backup command. This command performs the orchestration of a database consistent storage snapshot on the DATA volumes, and a storage snapshot (without any database consistency setup) on the OTHER volumes.

For DATA volumes azacsnap prepares the database for a storage snapshot, then it takes a storage snapshot for all configured volumes, finally it tells the database the snapshot is complete. It also manages any database entries which record snapshot backup activity (for example, SAP HANA backup catalog).

Command options

The -c backup command takes the following arguments:

  • --volume= type of volume to snapshot, this parameter may contain data, other, or all

    • data snapshots the volumes within the dataVolume stanza of the configuration file.
      1. data Volume Snapshot process
        1. put the database into backup-mode.
        2. take snapshots of the Volumes listed in the configuration file's "dataVolume" stanza.
        3. take the database out of backup-mode.
        4. perform snapshot management.
    • other snapshots the volumes within the otherVolume stanza of the configuration file.
      1. other Volume Snapshot process
        1. take snapshots of the Volumes listed in the configuration file's "otherVolume" stanza.
        2. perform snapshot management.
    • all snapshots all the volumes in the dataVolume stanza and then all the volumes in the otherVolume stanza of the configuration file. The processing is handled in the order outlined as follows:
      1. all Volumes Snapshot process
        1. data Volume Snapshot (same as the normal --volume data option)
          1. put the database into backup-mode.
          2. take snapshots of the Volumes listed in the configuration file's "dataVolume" stanza.
          3. take the database out of backup-mode.
          4. perform snapshot management.
        2. other Volume Snapshot (same as the normal --volume other option)
          1. take snapshots of the Volumes listed in the configuration file's "otherVolume" stanza.
          2. perform snapshot management.

    Note

    By creating a separate config file with the boot volume as the otherVolume, it's possible for boot snapshots to be taken on an entirely different schedule (for example, daily).

  • --prefix= the customer snapshot prefix for the snapshot name. This parameter has two purposes. Firstly provide a unique name for grouping of snapshots. Secondly to determine the --retention number of storage snapshots that are kept for the specified --prefix.

    Important

    Only alpha numeric ("A-Z,a-z,0-9"), underscore ("_") and dash ("-") characters are allowed.

  • --retention the number of snapshots of the defined --prefix to be kept. Any extra snapshots are removed after a new snapshot is taken for this --prefix.

  • --trim available for SAP HANA v2 and later, this option maintains the backup catalog and on disk catalog and log backups. The number of entries to keep in the backup catalog is determined by the --retention option above, and deletes older entries for the defined prefix (--prefix) from the backup catalog, and the related physical logs backup. It also deletes any log backup entries that are older than the oldest non-log backup entry. This --trim operation helps to prevent the log backups from using up all available disk space.

    Note

    The following example command will keep 9 storage snapshots and ensure the backup catalog is continuously trimmed to match the 9 storage snapshots being retained.

    azacsnap -c backup --volume data --prefix hana_TEST --retention 9 --trim

  • [--flush] an option to request the operating system kernel to flush I/O buffers for volumes after the database is put into "backup mode". In prior versions we used the "mountpoint" values to indicate volumes to flush, with AzAcSnap 10 the --flush option will take care of it. Therefore this key/value ("mountpoint") can be removed from the configuration file.

    • On Windows volumes which are labelled as "Windows" or "Recovery", and are NTFS will not be flushed. You can also add "noflush" to the volume label and it will not be flushed.
    • On Linux all I/O is flushed using the Linux sync command.

    Running the following example on the same host running the database will:

    1. Put the database into "backup mode".
    2. Request an operating system kernel flush of I/O buffers for local volumes (see operating system specific details).
    3. Take a storage snapshot.
    4. Release the database from "backup mode".
    azacsnap -c backup --volume data --prefix hana_TEST --retention 9 --trim --flush

  • [--ssl=] an optional parameter that defines the encryption method used to communicate with SAP HANA, either openssl or commoncrypto. If defined, then the azacsnap -c backup command expects to find two files in the same directory, these files must be named after the corresponding SID. Refer to Using SSL for communication with SAP HANA. The following example takes a hana type snapshot with a prefix of hana_TEST and keeps 9 of them communicating with SAP HANA using SSL (openssl).

    azacsnap -c backup --volume data --prefix hana_TEST --retention 9 --trim --ssl=openssl

  • [--configfile <config filename>] is an optional parameter allowing for custom configuration file names.

Snapshot backups are fast

The duration of a snapshot backup is independent of the volume size, with a 10-TB volume being snapped within the same approximate time as a 10-GB volume.

The primary factors impacting overall execution time are the number of volumes to be snapshot and any changes in the --retention parameter (where a reduction can increase the execution time as excess snapshots are removed).

In the example configuration provided for Azure Large Instance, snapshots for the two volumes took less than 5 seconds to complete. For Azure NetApp Files, snapshots for the two volumes would take about 60 seconds.

Note

If the --retention is significantly reduced from the previous time azacsnap is run (for example, from --retention 50 to --retention 5), then the time taken will increase as azacsnap needs to remove the extra snapshots.

Example with data parameter

azacsnap -c backup --volume data --prefix hana_TEST --retention 9 --trim

The command doesn't output to the console, but does write to a log file, a result file, and /var/log/messages.

In this example, the log file name is azacsnap-backup-azacsnap.log (see Log files).

When running the command -c backup with the --volume data option, a result file is also generated as a file to allow for quickly checking the result of a backup. The result file has the same base name as the log file, with .result as its suffix.

In this example, the result file name is azacsnap-backup-azacsnap.result and contains the following output:

cat logs/azacsnap-backup-azacsnap.result

Database # 1 (H80) : completed ok

The /var/log/messages file contains the same output as the .result file. See the following example (run as root):

grep "azacsnap.*Database" /var/log/messages | tail -n10

Jul  2 05:22:07 server01 azacsnap[183868]: Database # 1 (H80) : completed ok
Jul  2 05:27:06 server01 azacsnap[4069]: Database # 1 (H80) : completed ok
Jul  2 05:32:07 server01 azacsnap[19769]: Database # 1 (H80) : completed ok
Jul  2 05:37:06 server01 azacsnap[35312]: Database # 1 (H80) : completed ok
Jul  2 05:42:06 server01 azacsnap[50877]: Database # 1 (H80) : completed ok
Jul  2 05:47:06 server01 azacsnap[66429]: Database # 1 (H80) : completed ok
Jul  2 05:52:06 server01 azacsnap[82964]: Database # 1 (H80) : completed ok
Jul  2 05:57:06 server01 azacsnap[98522]: Database # 1 (H80) : completed ok
Jul  2 05:59:13 server01 azacsnap[105519]: Database # 1 (H80) : completed ok
Jul  2 06:02:06 server01 azacsnap[114280]: Database # 1 (H80) : completed ok

Example with other parameter

azacsnap -c backup --volume other --prefix logs_TEST --retention 9

The command doesn't output to the console, but does write to a log file only. It does not write to a result file or /var/log/messages.

In this example, the log file name is azacsnap-backup-azacsnap.log (see Log files).

Example with other parameter (to backup host OS)

Note

The use of another configuration file (--configfile bootVol.json) which contains only the boot volumes.

azacsnap -c backup --volume other --prefix boot_TEST --retention 9 --configfile bootVol.json

Important

For Azure Large Instance, the configuration file volume parameter for the boot volume might not be visible at the host operating system level. This value can be provided by Microsoft Operations.

The command doesn't output to the console, but does write to a log file only. It does not write to a result file or /var/log/messages.

In this example, the log file name is azacsnap-backup-bootVol.log (see Log files).

Log files

The log file name is constructed from the following "(command name)-(the -c option)-(the config filename)". For example, if running the command azacsnap -c backup --configfile h80.json --retention 5 --prefix one-off then the log file is called azacsnap-backup-h80.log. Or if using the -c test option with the same configuration file (e.g. azacsnap -c test --configfile h80.json) then the log file is called azacsnap-test-h80.log.

Note

Log files can be automatically maintained using this guide.

Next steps