[linux-lvm] Why does every lvm command insist on touching every pv?

[Takahiro Yasui]

On 06/15/10 13:46, Phillip Susi wrote:
> On 6/15/2010 12:47 PM, Alasdair G Kergon wrote:
>> It shouldn't normally scan unless it detects something might have changed, but
>> if you know the volume group name(s) already, put them on the command line: 
>>   lvs vg1 vg2
>>
>> (As always -vvvv may give you clues as to what is triggering the scan.)
> 
> I can see from the output with -vvvv that it is indeed trying to find a
> pv label on every block device in /dev.  I thought that I had figured
> out this was because lvm.conf was setting scan = [ "/dev" ] in the
> devices section, but I tried removing /dev, and just setting it to "",
> as well as "none" and lvs -vvvv STILL is opening every block device in /dev.

Everytime lvm command is executed, all PVs are accessed.

This is a known issue and what we should fix. If there are a lot of
PVs, execution of lvm command could take a long time. The scan also
affects error recovery time of lvm mirror.

This is an old reference.

Introduce metadata cache feature
https://www.redhat.com/archives/lvm-devel/2009-April/msg00014.html

Thanks,
Taka