[linux-lvm] LVM commands extremely slow during raid check/resync

[Ray Morris]

> > so it was checking LVs to see if they
> > were PVs ...
> > The solution was to use "filter" in lvm.conf like this:

> Could you check upstream  CVS version of lvm2 with 2 extra patches:
> (not yet upstream)
> 
> https://www.redhat.com/archives/lvm-devel/2012-March/msg00171.html
> https://www.redhat.com/archives/lvm-devel/2012-March/msg00172.html
> 
> Whether your slow PV operations are solved ?

Patch #2 seems to apply when they are a lot of PVs. In our case, we 
have very few PVs and a lot of LVs, so I don't think it would affect
us. Patch #1 is a bit less clear to me. Is it applicable to an
environment with few PVs? 
-- 
Ray Morris
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On Tue, 27 Mar 2012 16:31:49 +0200
Zdenek Kabelac <zkabelac at redhat.com> wrote:

> Dne 26.3.2012 22:55, Ray Morris napsal(a):
> > Put -vvvv on the command and see what takes so long. In our case, 
> > it was checking all of the devices to see if they were PVs.
> > "All devices" includes LVs, so it was checking LVs to see if they
> > were PVs, and activating an LV triggered a scan in case it was 
> > a PV, so activating a volume group was especially slow (hours).
> > The solution was to use "filter" in lvm.conf like this:
> > 
> > filter = [ "r|^/dev/dm.*|", "r|^/dev/vg-.*|","a|^/dev/sd*|",
> > "a|^/dev/md*|", "r|.*|" ]
> > 
> > That checks only /dev/sd* and /dev/md*, to see if they are PVs, 
> > skipping the checks of LVs to see if they are also PVs. Since the
> > device list is cached, use vgscan -vvvv to check that it's checking 
> > the right things and maybe delete that cache first. My rule IS 
> > a bit redundant because I had trouble getting the simpler form 
> > to do what I wanted. I ended up using a belt and suspenders 
> > approach, specifying both "do not scan my LVs" and "scan only
> > /dev/sd*".
> 
> Could you check upstream  CVS version of lvm2 with 2 extra patches:
> (not yet upstream)
> 
> https://www.redhat.com/archives/lvm-devel/2012-March/msg00171.html
> https://www.redhat.com/archives/lvm-devel/2012-March/msg00172.html
> 
> Whether your slow PV operations are solved ?
> 
> Zdenek
> 
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