From: Zdenek Kabelac <zkabelac@redhat.com>
To: LVM general discussion and development <linux-lvm@redhat.com>,
Zhiyong Ye <yezhiyong@bytedance.com>
Subject: Re: [linux-lvm] The feasibility of implementing an alternative snapshot approach
Date: Mon, 9 Jan 2023 23:18:36 +0100 [thread overview]
Message-ID: <255eaaae-e30b-2e69-cc03-38ca34902d16@redhat.com> (raw)
In-Reply-To: <ffd6b6d7-c197-1e3a-4b9b-c6fe8271a82d@bytedance.com>
Dne 09. 01. 23 v 7:21 Zhiyong Ye napsal(a):
> Hi Zdenek,
>
> Thank you for your detailed answer.
>
> For the thin snapshot I will use the latest version of kernel and lvm for
> further testing. I want to use both snapshot methods (thin and thick) in the
> production environment. But if the thick snapshot is only still in the
> maintenance phase, then for thick lv I have to see if there is any other way
> to accomplish the snapshot function.
FYI - there are still some delays with up-streaming of the latest improvement
patches - so stay tuned for further speedup gains & IO throughput with thin
provisioning)
By the maintenance phase for old thick snapshot I mean - the development of
the existing thick snapshot target is basically done - the format is very
ancient and cannot be changed without major rewrite of the whole snapshot
target as such - and that's what we've made with newly introduced
thin-provisioning target which addressed many shortcomings of the old
dm-snapshot target.
> I use lvm mainly for virtualized environments. Each lv acts as a block device
> of the virtual machine. So I also consider using qemu's own snapshot feature.
> When qemu creates a snapshot, the original image used by the virtual machine
> becomes read-only, and all write changes are stored in the new snapshot. But
> currently qemu's snapshots only support files, not block devices.
Depending on the use-case it might matter to pick the best fitting chunk-size.
i.e. if the changes are 'localized' in the filesystem areas to match thin-pool
chunks (also selection of the filesystem itself might be part of equation
here) - even if you use snapshots a lot, you may eventually get better result
with bigger chunks like 128k or even 256k size instead of default 64K.
Regards
Zdenek
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next prev parent reply other threads:[~2023-01-09 22:18 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-04 8:00 [linux-lvm] The feasibility of implementing an alternative snapshot approach Zhiyong Ye
2023-01-04 14:09 ` Zdenek Kabelac
2023-01-04 16:12 ` Zhiyong Ye
2023-01-06 13:42 ` Zdenek Kabelac
2023-01-09 6:21 ` Zhiyong Ye
2023-01-09 22:18 ` Zdenek Kabelac [this message]
2023-01-10 3:48 ` [linux-lvm] [External] " Zhiyong Ye
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