SR_BACKEND_FAILURE_109(, The snapshot chain is too long, )

PDANZ

Hi All

I have a fairly small setup. 1 XCP-NG host in a single pool with XO running on a VM hosted on a sybology box.

My W2k16 Server VM has rolling snapshots setup through XO to run every 2 hours 7 days a week between 8.30am and 6.30pm. The rentention policy is to keep 30 snap shots.

This VM also has a daily Delta Backup run at 9pm.

Only 2 other VM's on the host that run normal daily delta backups.

Nothing else other than these but I am now getting an error on the Rolling Snapshot task of "SR_BACKEND_FAILURE_109(, The snapshot chain is too long, )"

Is there a recommended limit on the number of snapshots a VM should have? I actually do not how to resolve this issue.

TIA
PD

PDANZ

Edit: I just had to wait until all the snapshots were merged and then the next backup worked fine.

Thanks Oliver for the response and advice.

I have removed the rolling snapshot task and will just keep the daily backup process.

How do I fix the error though, as I still get this issue even after I removed all the snapshots and that backup task.

This error is stopping the Delta backup task from running.

olivierlambert

Keeping 30 snapshots is not possible, because the max chain length is 25. Also, keeping more than few snapshots isn't a good thing especially due to the read performance impact.

Frankly, just make your backup and don't keep any extra snapshot, there's little value to have much more like this (maybe if you really need, a rolling snap of 1 or 2 is already nice).

Your backup is already protecting you, and a rolling snap is just a way to get back in time, not a real backup (you can manually snap before a specific operation if you need)

PDANZ

Edit: I just had to wait until all the snapshots were merged and then the next backup worked fine.

Thanks Oliver for the response and advice.

I have removed the rolling snapshot task and will just keep the daily backup process.

How do I fix the error though, as I still get this issue even after I removed all the snapshots and that backup task.

This error is stopping the Delta backup task from running.

olivierlambert

So you are back on track, right?

PDANZ

Yes all back on track. Just took some time for all the snapshots to be deleted (merged?).

Once complete I was able to run backups again as per normal.

olivierlambert

Yes, when you delete a snap, it must be coalesced. So everything is normal here. Switching the thread a solved, thanks for your feedback!