Chris Mason wrote:
On Thu, Jun 04, 2009 at 02:02:20PM -0500, Steven Pratt wrote:
Chris Mason wrote:
Hello everyone,
Yan Zheng has been doing some major surgery to the back references and
extent allocation code, tackling bottlenecks in the code that tracks
extents. It scales better with many snapshots and performs better in
the common case of no snapshots at all.
THE NEW CODE IS A FORWARD ROLLING DISK FORMAT CHANGE. This means it is
compatible with the current btrfs disk format, but once you mount a
filesystem with the new code, it WILL NO LONGER BE MOUNTABLE FROM OLD
KERNELS. Old kernels spit out an error message when you try them on new
format filesystems.
This is a large change, and I'm hoping to have it stable in time for the
2.6.31 merge window. I've been testing it for about a week now, and
haven't been able to cause major problems yet. But, testing the
compatibility with old format filesystems is the hard part, and
everyone that pulls the new code should backup their data first.
I've setup git branches called newformat where you can pull the new code.
For the kernel (based on 2.6.30-rc7):
git pull git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable.git
newformat
So I started the performance runs on this. The base tests completed fine
on the raid system and I will post results as soon as I can finish
postprocessing, but when I tried to do nodatacow that machine it crashed
pretty early. Here is console log:
Hi Steve,
Thanks again for hammering on these. Yan Zheng and I have both been
trying to reproduce problems with nodatacow and with the database random
write run.
So now that the raid machine is actually up, I discovered it got further
than I thought on nodatacow. It did all the read tests, but appeared to
died on 16 thread random write(not odirect). There were no messages
logged to var/log/messages at all. Last I saw was :
Jun 4 03:14:24 btrfs1 kernel: [65856.065491] btrfs: setting nodatacow
Jun 4 15:24:45 btrfs1 syslogd 1.4.1: restart.
Just dead until we rebooted machine later that day.
But, so far we haven't been able to trigger any crashes. Do you see
anything in your config or setup that is unusual?
No, other than using the old mkfs with the new format. I've kicked off
new runs to see if I hit the same issues
Steve
-chris
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