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Re: [Xen-users] Questions on qcow, qcow2 versus LVM

To: matt@xxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Questions on qcow, qcow2 versus LVM
From: Thiago Camargo Martins Cordeiro <thiagocmartinsc@xxxxxxxxx>
Date: Mon, 21 Dec 2009 11:04:06 -0200
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You can "ummount/free" the "not mounted"/busy LVMs LVs with dmsetup!  ;-)
Anyway, I agree this is sucks!

Are you using kpartx to map the LVs partitioned partitions to your dom0? If yes, try to not partition (with fdisk) a LV volume... Just use the LVs within your domUs as it is...


2009/12/21 Matthew Law <matt@xxxxxxxxxxxxxxxxxx>
I've been using lvm under centos to create the backing store for domUs and
although the performance seems acceptable it has some shortcomings.  The
biggest of which is the LVM bug which prevents me from removing an lv (it
says it is still mounted and it definitely isnt).  I thought this was just
a centos bug but it appears to be evident in debian and ubuntu too and I
really can't afford a reboot of the dom0 everytime I want to remove a
logical volume that was once accessed but now isn't!

What are people's experiences with using qcow or qcow2 images over LVM
volumes?  The reason I chose LVM was for it's ease of management and
relative ease with which you can shrink and enlarge a domU filesystem.
Can you do this with qcow?  How does it perform on a dom0 with many
running domUs (ie. dozens) ?



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