Do snapshots freeze fs before snapshotting ?

[facchettos]

What new functionality do you want?

Just some doc update, I could not find anywhere in the docs, whether or not when you create a snapshot the fs/block is frozen or not before the snapshot is taken. In the alpha description of volume snapshots (kubernetes), they talked about having to get the fs/bd into a frozen state before doing the snapshot but it disappeared in beta. I wonder if cephcsi does that or if someone that create snapshots should first make sure that the volumes are not in use before doing the snapshot ?

[Madhu-1]

Yes, it's the user's responsibility to make sure PVC is not in use before taking snapshots or creating the clone. Hope in feature, kubernetes will add a hook to do options to freeze the IO when we are taking snapshots or clone

[facchettos]

Thanks !
Do you think it is worth it to update https://github.com/ceph/ceph-csi/blob/master/docs/cephfs-snap-clone.md#snapshot and possibly for rbd too or not ?

[Madhu-1]

Yes please, @facchettos is it possible to send PR to update the doc?

[facchettos]

I'm on it =)

[Madhu-1]

Need changes here also https://github.com/ceph/ceph-csi/tree/master/examples#how-to-test-rbd-snapshot-feature

[humblec]

@facchettos true , volume should not be in use while snapshot is taken, this has been mentioned as a prerequisties in kube. However there is no enforcement happening from the controller . Also refer kubernetes-csi/external-provisioner#437

[facchettos]

Right, so the bigger point in the end is that ceph’s snapshots recommend the volume not to be in use while taking the snapshot ? ( https://docs.ceph.com/en/latest/rbd/rbd-snapshot/ )

[humblec]

Right, so the bigger point in the end is that ceph’s snapshots recommend the volume not to be in use while taking the snapshot ? ( https://docs.ceph.com/en/latest/rbd/rbd-snapshot/ )
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On Mon, 28 Sep 2020 at 17:57, Humble Devassy Chirammal < @.***> wrote: @facchettos https://github.com/facchettos true , volume should not be in use while snapshot is taken, this has been mentioned as a prerequisties in kube. However there is no enforcement happening from the controller . Also refer kubernetes-csi/external-provisioner#437 <kubernetes-csi/external-provisioner#437> — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1532 (comment)>, or unsubscribe https://github.com/notifications/unsubscribe-auth/AFNKIPXSPUD3Z7HB2WEBLULSICW55ANCNFSM4R4SDPQQ .

correct, also ceph as a storage provider offers crash consistent snapshots.