Bug#608532: marked as done (linux-2.6: very low I/O performance when vm's virtual disk placed on btrfs partition)
Your message dated Sat, 1 Jan 2011 18:31:35 +0100
with message-id <20110101173135.GB27075@wavehammer.waldi.eu.org>
and subject line Re: Bug#608532: linux-2.6: very low I/O performance when vm's virtual disk placed on btrfs partition
has caused the Debian Bug report #608532,
regarding linux-2.6: very low I/O performance when vm's virtual disk placed on btrfs partition
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
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--
608532: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=608532
Debian Bug Tracking System
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--- Begin Message ---
Package: linux-2.6
Version: 2.6.32-29
While I was running a qemu-kvm virtual machine, I placed the virtual
disk on one of my btrfs partition and it results in very low I/O
performance. Comparing with an Ext3/4 host partition, it slows several
times.
The test I ran was installing Squeeze using d-i beta2 netinst ISO
image, using expert installation mode:
1. The one using btrfs got nearly stopped at approximately 33% (it's
the time to start installing base system, i.e. installing
apt/aptitude). It takes about 1 hour to go forward to 50%, with my
hard disk making a lot of noise, and finally I shut down the virtual
machine.
2. The other one using ext4, which I tried to compare the performance,
can finish the installation in ~45 minutes.
The two partition are exactly the same hard disk, actually I formatted
the previous btrfs partition to ext4 when I ran the test.
--
Regards,
Aron Xu
--- End Message ---
--- Begin Message ---
On Sat, Jan 01, 2011 at 12:02:23PM +0800, Aron Xu wrote:
> While I was running a qemu-kvm virtual machine, I placed the virtual
> disk on one of my btrfs partition and it results in very low I/O
> performance. Comparing with an Ext3/4 host partition, it slows several
> times.
This is a result of the filesystem design, no bug. For decent
performance don't use O_SYNC on files. For qemu use cache=writeback in
the disk definition.
Bastian
--
There are always alternatives.
-- Spock, "The Galileo Seven", stardate 2822.3
--- End Message ---
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