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streaming and intellisnap backups for vSAN datastore

  • 31 March 2022
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In the following URL vSAN Support for the Virtual Server Agent with VMware (commvault.com), it is written “For Service Pack 11 and later, the Virtual Server Agent (VSA) provides support for streaming backups, IntelliSnap backups, and restores of virtual machines on VMware Virtual SAN (vSAN) datastores.”

In the case of  VMware vSAN, what is the difference between streaming & Intellisnap backups?

Is the hotadd transport mode linked to Intellisnap backups and the NBD transport mode linked to streaming backups?

Thanks & Regards

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Best answer by Peanut 31 March 2022, 19:26

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  Transport mode is a separate topic from streaming vs Intellisnap.  Basically Streaming backup will take a snapshot of the VM and starts streaming the data for backup.  This is against the live production VM.  Once the job is completed the snap is removed and the backup is completed.

  Regarding intellisnap, the process is a little different.  Intellisnap backups take a snapshot of the VM and then takes a hardware snapshot of the data store on the array.  We can then run a backup copy of the VM where we will stream the backup from the hardware snap which does not happen against the live production VM.

  For vSAN there is not a hardware snapshot on the array, instead a snapshot of the VM is created and left on the datastore until a backup copy is run or retention is met.

More info on vVol and vSan backup can be found here

https://documentation.commvault.com/11.24/expert/62400_intellisnap_protection_for_vms_on_vvol_or_vsanvxrail_datastores.html

 

Transport mode is based on how you have things configured.  

If your proxy is a VM you can do NBD transport or Hotadd

If your Proxy is a physical machine you can use NBD or SAN transport (If you have presented the datastores to the proxy machine)

https://documentation.commvault.com/11.24/expert/36340_transport_modes_for_vmware.html

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Thanks for your answer Peanut-)

Let me please summarize:

  1. In both types of backups (streaming & Intellisnap), VMware snapshots are executed.
  2. SAN transport mode is not supported for vSAN (since this is Direct Attached Storage)
  3. For vSAN, backups and restores can use HotAdd or NBD transport in both types of backups (streaming & Intellisnap)
  4. For streaming backups for vSAN, if you use hotadd transport mode (VM VSA Proxy): the VMDK disks of the VM to backup are mounted to the VM VSA Proxy. Afterwards, the data are sent from the VM VSA Proxy to the disk/cloud library over a Media Agent through the LAN (you could avoid LAN if VSA & MA are on the same machine). So, I guess there is no impact on the live Production VM because the backup traffic starts from the VM VSA Proxy and not from the live production VM.
  5. For an Intellisnap backup for vSAN, if you use NBD transport mode, when you run a backup copy to a disk/cloud library, I guess there is an impact on the live production VM because the backup copy is executed from the VMware snapshot which is linked to the live production VM.

Correct or I missed something?

Many Thanks for your feedback & support.

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There should be minimum impact as we are not running any commvault software on the production VM.  The only impact is on the datastore where the snapshot is located as we have the snapshot sitting there taking up space until it is removed.  No resources are used on the production VM only on the proxy that is backing up those snapshots.  The biggest impact in any VM backup will be during the taking and removing of the snapshots as there is a freeze/thaw process on the VM while the point in time snap is taken or while the changes are played back.  However this will typically have very little impact on most VM’s.

 

 

 

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Thanks for your feedback @Peanut .

 

But in fact, I had 2 questions 😀(please see below 1 & 2).

I guess you answered for my question 2 below (or 5 above). But what about the impact on the live VM with the streaming backups in a vSAN environment?

In your first answer above, you wrote “Basically Streaming backup will take a snapshot of the VM and starts streaming the data for backup.  This is against the live production VM.”

  1. For streaming backups for vSAN, if you use hotadd transport mode (VM VSA Proxy): the VMDK disks of the VM to backup are mounted to the VM VSA Proxy. Afterwards, the data are sent from the VM VSA Proxy to the disk/cloud library over a Media Agent through the LAN (you could avoid LAN if VSA & MA are on the same machine). So, I guess there is no impact on the live Production VM because the backup traffic starts from the VM VSA Proxy and not from the live production VM. Is it correct?
  2. For an Intellisnap backup for vSAN, if you use NBD transport mode, when you run a backup copy to a disk/cloud library, I guess there is an impact on the live production VM because the backup copy is executed from the VMware snapshot which is linked to the live production VM. So, apparently no real impact on the live VM except when taking and removing the snapshots. Correct?

Thanks for your feedback and involvement.

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hi @brucquat 

Well, @Peanut tried to explain you what could impact your production VM depending on the backup type you would chose : Streaming or Intellisnap backups.

For your 1st topic, the streaming backup performs a VMWare snapshot of the VM you need to backup, and when VMWare snapshot is complete, this snapshot is ‘mounted’ to your VSA Proxy/MA for backup.

From this VMWare snapshot, when all the VMDKs of the VMs would have been backup, Commvault tells VMWare to delete this VMWare snapshot. This means that if the backup took long, depending on this VM activity during the backup, the VMWare snapshot could be big and take long to be consolidated, impacting your ‘Live’/production VM during the consolidation phase.

 

For your 2nd topic, using Intellisnap would ask VMWare to perform a VMWare snapshot of the VM, then (as @Peanut explained it) it would perform a ‘hardware’ snapshot of the datastore where your VM is hosted, then when this is complete, Commvault would ask for the deletion of the VMWare snapshot, causing VMWare snapshot to be consolidated, as explained a bit above. As this operation would have taken far less time than the ‘streaming’ backup of topic 1, at this point in time, the VMWare snapshot should not have grown that much, reducing a lot its potential size (still compared to case 1), so minimizing the impact on the ‘live’/production VM. But at this moment, you do not have a real backup of the VM. Just a hardware snap of it. This is why you need to run a backup copy of this snapshot, that would basically work with the hardware-created snapshot for the backup of your VM. And this hardware snap would be deleted per your SPc settings, still not affecting your live VM.

 

This way you (should) have far less impact on your Prod VM using Intellisnap than using Streaming.

This would have more impact on your storage, then, as it would have to store (more) snapshots.

If you backup per VM, and you have one VM per Datastore, then it’s fine, as you’ll grab all your VMs in one single hardware snapshot.

If you have multiple VMs per Datastore and use Intellisnap, then make sure you don’t snap like 30TB for only 1 VM, and repeat the same for each VM.

 

VSAN support in Commvault is not as a Transport mode, but some Intellisnap hardware feature. 

Sorry for writing that much, but well, this lead me to multiple topics.. 😄

Regards,

Laurent.

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Many thanks for you detailed and clear answer.

Really appreciated.

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