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Is it safe to snapshot an attached volume if it's unmounted?

asked 2017-09-08 15:26:15 -0500

My OpenStack provider recommends against creating a snapshot backup of a volume if it's attached to an instance. But if the using instance has unmounted it, wouldn't this protect against data corruption?

Or are there other issues at play here?

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is that volume mounted for database , if its dbi would recommend take db backup instead of taking snapshot, snapshot genertally take more disk utilization this could be the reason your vender opposing to take snapshots

billy gravatar imagebilly ( 2017-09-08 16:38:43 -0500 )edit

Yes and no. I have one volume used by the Web server that's a regular file system, and another that's used by the DB server that houses MySQL data (/var/lib/mysql). I'd like to develop a backup policy that works and is safe in all cases.

colan gravatar imagecolan ( 2017-09-11 05:14:38 -0500 )edit

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answered 2017-09-11 05:16:58 -0500

updated 2018-02-16 11:55:07 -0500

Here's what I heard back from one ISP:

In this case, I would really recommend you to detach the disk to avoid corruption of data because even if it is unmounted the instance might still be risky because of the way openstack handles the disk.

I'm not sure what they mean by "handles the disk".

And here's what I heard from another, which makes more sense:

You can certainly snapshot a mounted volume, however we highly recommend that the server is powered off, or you have it unmounted within the filesystem.

So I think powering off the instance, snapshotting it, snapshotting any of its attached volumes, and then powering it on is probably the best way to go.

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Added response from another ISP.

colan gravatar imagecolan ( 2018-02-16 11:55:41 -0500 )edit

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Asked: 2017-09-08 15:26:15 -0500

Seen: 438 times

Last updated: Feb 16 '18