[linux-lvm] LVM2 robustness w/ large (>100TB) name spaces?

Steve Costaras stevecs at chaven.com
Tue Dec 23 01:33:36 UTC 2008

Thanks, I was planning on using a larger metadata area anyway, just to play
it safe as I'm expecting a 3-4x growth for the life of the array before next
hard rebuild and all the comments I've seen on the Inet are talking about
much smaller array sizes than what I'm building.     Is there any rule of
thumb or sizing guidelines or is it a black art?

With PE/LE's being 32bit (or is it a signed 32bit so 31 bits?)  Either way,
that's more than enough even w/ 4MiB sizes for the expected end-state of the
name space.


-----Original Message-----
From: linux-lvm-bounces at redhat.com [mailto:linux-lvm-bounces at redhat.com] On
Behalf Of Alasdair G Kergon
Sent: Monday, December 22, 2008 19:25
To: LVM general discussion and development
Subject: Re: [linux-lvm] LVM2 robustness w/ large (>100TB) name spaces?

 From the LVM2 point of view, extents (PEs/LEs) are counted using 32-bit
numbers so that's where the limit comes from.
(You can change extent size later, shuffling extent boundaries with pvmove
first as necessary.)

The stripe size is controlled by a separate parameter essentially
independent of the PE size.

When creating the PVs, use a larger-than-default size for the metadata area:
it is awkward to change later if you fill it up.

agk at redhat.com

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