vSAN Backup and SPBM policies.
I get asked a lot of questions about how Backup works with vSAN. For the most part it’s a simple request for a vendor support statement and VADP/CBT documentation. The benefit of native vSAN snapshots (better performance!) does come up, but I will point out there is more to backup and restores than just the basics. Lets look at how one vendor (Veeam) integrates SPBM into their backup workflow.
Storage Based Policies can tie into availability and restore planning. When setting up your Backup or Replication software make sure that it supports the ability to restore a VM to it’s SPBM policy, as well as have the ability to do custom mapping. You do not want to have to do a large restore job then after the restore re-align block locations again to apply a policy if only the default cluster policy is used for restores. This could result in a 2x or longer restore time. Check out this Video for an example of what Backup and Restore SPBM integration looks like.
While some questions are often around how to customize SPBM policies to increase the speed of backups (on Hybrid possibly increase a stripe policy), I occasionally get questions about how to make restores happen more quickly.
A common situation for restores is that a volume needs to be recovered and attached to a VM simple to recover a few files, or allow temporarily access to a retired virtual machine. In a perfect world you can use application or file level recovery tools from the backup vendor but with some situations an attached volume is required. Unlike a normal restore this copy of data being recovered and presented is often ephemeral. In other cases, the speed of recovery of a service is more important than the protection of it’s running state (maybe a web application server that does not contain the database). In both these cases I thought it worth looking at creating a custom SPBM policy that favored speed of recovery, over actual protection.
In this example I’m using a Failure To Tolerate (FTT) of 0. The reason for this is two fold.
- Reduce the capacity used by the recovered virutal machine or volume.
- Reduce the the time it takes to hydrate the copy.
In addition I’m adding a stripe width of 4. This policy will increase the recovery speed by splitting the data across multiple disk groups.
Now it should be noted that some backup software allows you to a run a copy from the backup software itself (Veeam’s PowerNFS server is an example). At larger scale this can often tax the performance of the backup storage itself. This temporary recovery policy could be used for some VM’s to speed to recovery of services when protection of data can be waived for the short term.
Now what if I decide I want to keep this data long term? In this case I could simple change the policy attached to the disk or VM to a safer FTT=1 or 2 setting.