Backup, CR and snapshots question
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Hello world,
I've been using XenServer for years and the combination of XCP-NG and XenOrchestra is a breath of fresh air.
I'm running the following setup, with two VMs running on three separate XCP-NG hosts (no shared storage):
- Site 1:
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- Host 1: 1TB local array, running VM A
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- Host 2: 1TB local array, running VM B
- Site 2:
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- Host 3: Offsite, 1TB local array, running no VMs.
Both VM A and B have a single 300GB disk created for them.
I then use continuous replication of VM A from host 1 to hosts 2 and 3 and VM B from host 2 to host 1 and 3.
The idea is to be able to survive a catastrophic failure of their main hosts and also if the main site goes offline.Given that XenServer was a bit peculiar in the past with storage (ex: not able to reclaim disk space online after deleting a snapshot in older versions if I remember correctly), I have a few questions to double-check and I won't run into limitations in the future.
I'm also running with local storage with thick provisioning, the local storage is mechanical SAS drives so I don't want to lose performance with fragmentation all over the place.
My questions are:
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Is it "safe" to use continuous replication for this kind of scenario and could this be done hourly with no long-term issues? I.e.: will 4 years from now (when XCP-NG LTS 8.2 will near EOL
) will this not cause to run into weird errors because the VM has been snapshotted/imported/exported tens of thoudsands of times. From what I understand in your documentation, coalescing fixes this so it should be fine. -
Knowing that each host has 1TB local storage, will it be enough place to continue using CR and even snapshots from time to time?
Let me explain:
In the past, I tried labbing with 400GB storage VMs, but it refused to create snapshots (from what I understand, XCP-NG wanted to see the whole 400GB space available). (400GB VM + 400 GB CR = less than 400GB remaining)
Now I use 300GB disk space VMs, so 300GB VM + 300GB CR = more than 300 GB remaining
Is there any other limitation that I should be aware?
I also want to use temporary snapshots before major upgrades on the VM, just in case. But those snapshots would be quickly deleted after I confirm the upgrade went correctly. I suppose the disk space would be reclaimed after deleting the snapshot, right?
Thanks!
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- Correct, no problem to do that
- No other limitation.
- Yes, space will be reclaimed thanks to coalesce after that.
