From: Thomas Lamprecht <t.lamprecht@proxmox.com>
To: "Proxmox Backup Server development discussion"
<pbs-devel@lists.proxmox.com>,
"Fabian Grünbichler" <f.gruenbichler@proxmox.com>
Subject: Re: [pbs-devel] [PATCH proxmox-backup 2/2] fix #5982: garbage collection: check atime updates are honored
Date: Tue, 18 Feb 2025 12:53:01 +0100 [thread overview]
Message-ID: <585ffd32-8868-44e5-91ee-df1eb2b2c87e@proxmox.com> (raw)
In-Reply-To: <1739806100.hejephfmgd.astroid@yuna.none>
Am 17.02.25 um 16:36 schrieb Fabian Grünbichler:
> On February 17, 2025 2:12 pm, Christian Ebner wrote:
>> Check if the filesystem the chunk store is located on actually
>> updates the atime when performing the marking of the chunks in
>> phase 1 of the garbage collection. Since it is not enough to check if
>> a single/first chunks atime is updated, since the filesystem can be
>> mounted via the `relatime` option, find the first chunk which is'
>> outside the relatime's 24 hour cutoff window and check the update on
>> that chunk only.
>
> given that our touching should punch through relatime (and does so on
> all filesystems we tested so far), couldn't we just
>
> - stat the first chunk
> - touch the first chunk
> - check if timestamps have been updated
> - print a warning about the filesystem being potentially broken, and
> - if the option is enabled, suggest the user report the details to us
> - only continue if the option is explicitly disabled
>
> that way we should get a real world survey of broken file systems that
> could inform our decision to drop the 24h window (or keep it).. if we
> introduce an option (defaulting to yes for now) conditionalizing the 24h
> window, we could even tell users with semi-broken storages (see below)
> to explicitly set that option in case we later switch the default,
> although I am not sure whether such storages exist for real.
+1; one (additional) option _might_ be to trigger suck a check on
datastore creation, e.g. create the all-zero chunk and then do that
test. As of now that probably would not win us much, but if we make
the 24h-wait opt-in then users would be warned early enough, or we
could even auto-set that option in such a case.
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next prev parent reply other threads:[~2025-02-18 11:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-17 13:12 [pbs-devel] [PATCH proxmox proxmox-backup 0/2] fix #5892: check atime update is honored Christian Ebner
2025-02-17 13:12 ` [pbs-devel] [PATCH proxmox 1/2] pbs api types: Add check garbage collection atime updates flag Christian Ebner
2025-02-17 13:12 ` [pbs-devel] [PATCH proxmox-backup 2/2] fix #5982: garbage collection: check atime updates are honored Christian Ebner
2025-02-17 15:36 ` Fabian Grünbichler
2025-02-17 15:57 ` Christian Ebner
2025-02-18 11:53 ` Thomas Lamprecht [this message]
2025-02-18 12:39 ` Christian Ebner
2025-02-18 13:17 ` Christian Ebner
2025-02-18 13:31 ` Thomas Lamprecht
2025-02-18 13:38 ` Christian Ebner
2025-02-19 16:54 ` [pbs-devel] [PATCH proxmox proxmox-backup 0/2] fix #5892: check atime update is honored Christian Ebner
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