Re: [Xen-devel] LVM performance problems with large number of VGs

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Fri, 1 Apr 2016, Syed Mushtaq wrote:
> Hi,
> 
> I am testing out a system in which each Guest disk is mapped to a LUN on a 
> backend storage. I am using Xenserver 6.5 for this and creating an SR with a 
> single VDI inside it for each Guest disk.
> The way it would work is, from an LVM point of view, I would have a Volume 
> Group (VG) for each virtual disk and a single logical volume (LV) inside that 
> VG. What I am seeing is that creating new
> volume groups is taking a lot of time. In my test after creating about 600 
> volume groups, it took about 4 seconds to create a new one. I have observed 
> this to be a linear trend where the more
> VGs I add the slower future operations become. Other operations like getting 
> the logical volumes inside a VG have also slowed down (even though there is 
> only 1 LV per VG).
> 
> I was wondering if anyone here faced a similar problem or had some experience 
> in dealing with LVM bottlenecks.

It doesn't seem like this is related to Xen, so I would recommend that you 
ask in the linux-lvm [0] mailing list. TBH, I have no idea how well LVM 
scales in these kind of scenarios.

Roger.

[0] https://www.redhat.com/mailman/listinfo/linux-lvm

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