From: Ming-Hung Tsai <mingnus@gmail.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] How to check if thin volume or snapshot was ever activated
Date: Mon, 9 Aug 2021 11:53:46 +0800 [thread overview]
Message-ID: <CAAYit8S5RZ8wh0WAxWEyuJJ=ejVd+TOXqUDFLhMLDGNEGhhRjQ@mail.gmail.com> (raw)
In-Reply-To: <7956b86706382158e1fddb3c4bfbfde3@assyoma.it>
On Sat, Aug 7, 2021 at 7:43 PM Gionatan Danti <g.danti@assyoma.it> wrote:
>
> Dear all,
> as you know, a thin snapshot does have the "k" (skip activation) flag
> set, so one has to force activation by ignoring the flag (or removing
> the flag itself).
>
> I wonder: can we detect if a volume/snapshot was *ever* activated? My
> reasoning is that a never-activated snapshot surely did not receive any
> application writes, so it can be safely removed (ignoring snapshot
> retention policy).
It sounds like you intend to keep snapshots that have been updated
(written) since its creation, right?
The precise way might be checking the data mappings via thin_dump. An
updated device has data mappings with timestamps greater than the
device's creation time.
Checking device activation might not meet what you need. An activated
device might or might not receive any write, so you don't know whether
a device has been updated by looking into its activation history.
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next prev parent reply other threads:[~2021-08-09 3:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-07 11:39 [linux-lvm] How to check if thin volume or snapshot was ever activated Gionatan Danti
2021-08-09 3:53 ` Ming-Hung Tsai [this message]
2021-08-09 4:16 ` Ming-Hung Tsai
2021-08-09 8:33 ` Gionatan Danti
[not found] ` <CAAYit8RWCA3W0y4vuZju6aZVSeu7e6SjErkZ1orLceJj0nhsvw@mail.gmail.com>
2021-08-10 8:46 ` Gionatan Danti
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