VM backup and Intellisnap

Last post 12-23-2016, 12:47 PM by Victor Ma. 7 replies.
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  • VM backup and Intellisnap
    Posted: 12-19-2016, 10:17 AM

    My understand of VM backup is that it take a VM snapshot before backup, and VM can resume it's read/write after the snapshot, and CommVault start to backup the snapshot. Is this for equivlent purpose of Intellisnap.

    If that is true, I should be able to use pre/post Snap script with VM backup?

    If I can, how do I run pre/post snap script on each of the VMs in one subclient?

    Sorry that there are too many questions. They are one lead to antoher, to understand if VM snapshot is for equivlent purose of Intellisna.

  • Re: VM backup and Intellisnap
    Posted: 12-19-2016, 3:33 PM

    As far as i know ,intellisnap is a hardware based protocol in which VM is snapshot at underlying hardware which is pretty fast and VM is able to resume it read and write operations as soon as the snapshot completes .So basically you can run a independent snapshot copy job to move the snapshots to media.

    I don't think you would be able to use pre and post script while performing vmware intellisnap .Even the link below only talks about software snapshots.

    http://documentation.commvault.com/commvault/v11/article?p=products/vs_vmware/t_vmw_config_pre_post_snap_script.htm

  • Re: VM backup and Intellisnap
    Posted: 12-20-2016, 6:36 AM

    Hi guys,

    the IntelliSnap backup of a VM does exactly the same as "streaming" backup. Only difference is, the instead of datamovement, a hardware Snapshot is created.

    1. create VM SnapShot via vCenter or ESXi Host
    2. backup VM (either datamovement / streaming using vStorage API or Hardware Snapshot of underlying datastores)
    3. remove VM SnapShot via vCenter or ESXi Host

    In case of IntelliSnap you can now create a backup copy of the VMs in the snapshot.

    pre / post scripts per VM are issued during create VM Snapshot / remove VM Snapshot phase.
    so the above mentioned link gives you all the information needed.

    if you follow this link, the pre/post scripts might be run automatically for each VM snapshot you create. Not only the one you request for you backup. so please test your scripts :)

    regards
    Klaus 

  • Re: VM backup and Intellisnap
    Posted: 12-20-2016, 10:41 AM

    That make a lot of sense, Klaus.

    then I still don't understand why we need another Snapshot(Hardware) on top of the VM SnapShot?

    • I understand the hardware snapshot is instant, but if I don't want to leave a snapshot on SAN all the time, aka always to a BAckup Copy immediately, and remove the snapshot, it's not faster than using datamovemnt/streaming.
    • If this is for end users need instant restore from snapshot, they can just leave VM Snapshot, or leave Hardware Snapshot there, why both?
    • Or is that because these 2 snapshots are from 2 different branches of technical solutions, and they are now come to this crossing point where both of them can be used, and CommVault can't just choose one of them?
  • Re: VM backup and Intellisnap
    Posted: 12-21-2016, 4:06 AM

    Hi Victor Ma,

    creating the Hardware Snapshot inside the storage array is considered to be your backup.

    you can (live) mount VMs from the hardware snapshot and (not on all arrays) restore them using Storage vMotion.
    If talking of SAN / NAS datastores, you can select the datastore as content of a subclient and all VMs holding data on this datastore will be (vmware) snapshoted, then a hardware snapshot is taken and the VM snapshots are removed again.
    VM snapshot life is very short in this scenario compared to a streaming backup. Therefore  the removal of VM snapshots can be faster since less delta data has to be applied to the original vmdk.

    later you can use AuxCopy (in case of netapp snapvault) and/or backupcopy (streaming backup) to enable your primary hardware snapshots to age.

    if your doing backup 2 disk, the storage vmotion feature is also available, but might be slower due to dedup (which will reduce restore speed due to fragmentation over time).

    w/ streaming backups (only) you have more flexible methods of selecting VMs to backup (like tags or comments to the VM), while intellisnap gives you the option to backup (more or less offsite) from a snapshot instead of the live data.
    In terms of backup speed (on streaming backups), it might also be possible to use incremental and syntetic full (only useful on backup 2 disk) backups  instead of incremental and full, to reduce the VM snapshot time.

    in my expierience a backup of 150VMs can be achieved in less then 1 hour (independent of the overall size) using intellisnap. Data movement (streaming / BackupCopy) depends on the amount of changed blocks and can be a longer process.

    on the other hand using intellisnap and backupcopy will add extra time to the backup process, since all  (snapshot) datastores have to be mouted on a mount ESX host and all VMs (from the backup) have to be registered during the backup.

    as always : it depends Smile

    have fun
    Klaus 

  • Re: VM backup and Intellisnap
    Posted: 12-21-2016, 10:04 AM

    Thanks for explaining with all these details.  So, there are a lot of benifit for leaving the Snapshot on SAN, and it is considered my backup. So it is not necessary to age them immediately. I will mark this question solved! 

    It's nice if someone can answer this quesion:-  However, can I consider my VM Snapshot to be my backup? I thought the answer is no, because the delta disk might grow too big before I aging it, it doesn't make sense due to performance penalty. Now, I don't know how hardware snapshot on SAN is taken, but I assume it is similar to VM Snapshot, and will have similar performance penalty?

  • Re: VM backup and Intellisnap
    Posted: 12-23-2016, 5:40 AM

    Hi Victor,

    to be honest, I wouldn't rely on a Hardware SnapShot inside the storage system to be my (final) backup !

    In general this snapshot is dependend on the live data (only delta is held in snapshot area or pointers are reaasigning the live data to new blocks if written) and if your primary volume (or underlying RAID groups) go corrupt, you also loose your backup !

    I would always try to get the data out of the primary storage system and into a secondary storage system, preferably in a different (datacenter) location.
    Only (out-of-the-box) hardware snapshot solution I know is NetApp using SnapVault, for all other array types you have to create a backupcopy to get the data out of the primary. 

    Dependend on the algorythm that is used to create / maintain the hardware snapshots, the existence of snapshots can have a performance impact on your primary data as well.
    So you should really make up your mind about the actual configuration and the impact on your live data.

    have fun
    Klaus 

  • Re: VM backup and Intellisnap
    Posted: 12-23-2016, 12:47 PM

    Thanks for the confirmation. It's much clear to me now.

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