[linux-lvm] When and why vgs command can change metadata and incur old metadata to be backed up?

[Gionatan Danti]

Il 30-10-2017 18:04 David Teigland ha scritto:
> On Mon, Oct 30, 2017 at 02:06:45PM +0800, Eric Ren wrote:
>> Hi all,
>> 
>> Sometimes, I see the following message in the VG metadata backups 
>> under
>> /etc/lvm/archive:
>> 
>> """
>> contents = "Text Format Volume Group"
>> version = 1
>> 
>> description = "Created *before* executing 'vgs'"
>> """
>> 
>> I'm wondering when and why the new backups will be created by 
>> reporting
>> command like vgs?
> 
> It's probably a case where lvm sees something wrong after reading the 
> VG
> metadata, and automatically tries to fix it, writing a corrected 
> version
> of the metadata to disk.  This means that even a command that only 
> reads
> and reports lvm information can potentially write to disk.

Interesting. Eric, can you show the *before* and *after* vgs textual 
metadata (you should find them in /etc/lvm/archive)?

> that in theory are only reading and reporting information.  I've also
> suggested that whenever repairs are done, lvm should record a 
> persistent
> message in the system log with the details, but that idea didn't get a
> great reception.

Just to know: why the idea of syslog reporting was discarded?

Thanks.

-- 
Danti Gionatan
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