On Mon, Feb 27, 2012 at 7:54 AM, dima [off-list ref] wrote:

Hello,

Since several people asked to post the results, here they are.
I tried raw virtio disk with and without -z -C set and also qcow2 vir=

tio

disk without -z -C set and did not notice any difference in performan=

ce at

all - Redhat 6.2 Minimal installs in 10 minutes in each case. The "ab=

ysmal"

performance as it was some several months ago (like 10 minutes just f=

or

virtual disk formatting) under the same conditions is no more at leas=

t on

3.3.0-rc5.

Just to make sure, this is a _new_ virtual disk right? I can barely
contain my excitement right now. This is amazing progress.

best
~dima



On 02/24/2012 02:22 PM, dima wrote:

quoted

On 02/13/2012 04:17 PM, Ralf-Peter Rohbeck wrote:

quoted

Hello,
is it possible to set nodatacow on a per-file basis? I couldn't fin=

d

quoted

quoted

anything.
If not, wouldn't that be a great feature to get around the performa=

nce

quoted

quoted

issues with VM and database storage? Of course cloning should still
cause COW.

Hello,
Going back to the original question from Ralf I wanted to share my
experience.

Yesterday I set up KVM+qemu and set -z -C with David's 'fileflags'
utility for the VM image file.
I was very pleased with results - Redhat 6 Minimal installation was
installed in 10 minutes whereas it was taking 'forever' the last tim=

e I

quoted

tried it some 4 months ago. Writes during installation were very
moderate. Performance of VM is excellent. Installing some big packag=

es

quoted

with yum inside VM goes very quickly with the speed indistinguishabl=

e

quoted

from that of bare metal installs.

I am not quite sure should this improvement be attributed to the noc=

ow

quoted

and nocompress flags or to the overall improvement of btrfs (I am on
3.3-rc4 kernel) but KVM is definitely more than usable on btrfs now.

I am yet to test the install speed and performance without those fla=

gs

quoted

set.

best
~dima
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