|Matt Simerson||Dec 18, 2008 10:19 am|
|Andrew Snow||Dec 18, 2008 4:12 pm|
|Wes Morgan||Dec 18, 2008 4:47 pm|
|Matt Simerson||Dec 18, 2008 9:37 pm|
|James R. Van Artsdalen||Dec 19, 2008 12:57 am|
|Zaphod Beeblebrox||Dec 19, 2008 9:29 am|
|Matt Simerson||Dec 23, 2008 12:43 pm|
|Adam McDougall||Dec 23, 2008 7:47 pm|
|Matt Simerson||Dec 24, 2008 10:34 pm|
|Subject:||Re: ZFS performance gains real or imaginary?|
|From:||Matt Simerson (ma...@corp.spry.com)|
|Date:||Dec 24, 2008 10:34:24 pm|
On Dec 24, 2008, at 9:29 PM, Adam McDougall wrote:
On Wed, Dec 24, 2008 at 01:00:14PM -0800, Matt Simerson wrote:
On Dec 23, 2008, at 7:48 PM, Adam McDougall wrote:
On Tue, Dec 23, 2008 at 12:43:47PM -0800, Matt Simerson wrote:
On Dec 18, 2008, at 4:12 PM, Andrew Snow wrote:
If so, then I really should be upgrading my production ZFS servers to the latest -HEAD.
Thats correct, that is the only way to get the best working version of ZFS. Of course, then everything is unstable and broken - eg. SMBFS became unusable for me and would crash the server.
Unfortunately, the newer kernel hangs much more frequently.
I have these settings in /boot/loader.conf
vm.kmem_size="1536M" vm.kmem_size_max="1536M" vfs.zfs.arc_max="100M"
I have also experimented with vfs.zfs.prefetch_disable, vfs.zfs.arc_min in the past, and I'm open to suggestions on what might help under this workload (multiple concurrent rsync processes from remote systems to this one).
Can you try:
vm.kmem_size=2G vm.kmem_size_max=2G vfs.zfs.arc_max=512M
This has been working for me on one amd64 system that only has 2G of ram but had similar problem frequency to yours. I don't know if its coincidence with the data that I am rsyncing lately, but: 10:47PM up 22 days, 7:12
I made it 23 minutes. I've reduced my rsync concurrency to 1, so I'm not hitting the system nearly as hard but it seems not to matter.
Other workloads, like a 'make buildworld' will complete with no problems. For whatever reason, rsync sessions of entire unix systems to my backup servers are very troublesome.
Ok. Since you have 16G of ram, I suppose you could try setting both kmem sizes to something like 8G to see if it makes a difference? I'm getting a feeling that even if we don't see an outright failure, it might be deadlocking due to a kmem shortage.
back01# w 10:17PM up 40 mins, 2 users, load averages: 4.20, 3.07, 1.74
This is with:
vm.kmem_size="4G" vm.kmem_size_max="4G" vfs.zfs.arc_max="512M"
I'll let it trundle along with that setting and see how long it lasts.
PS: These settings earlier today resulted in 12+ hours of uptime, until I rebooted to test raising kmem_size to 4G.
vm.kmem_size="2G" vm.kmem_size_max="2G" vfs.zfs.arc_max="512M" vfs.zfs.zil_disable=1 vfs.zfs.prefetch_disable=1
PPS: If/when it hangs with 4G, I'll raise it again to 6 or 8 GB and see how long it lasts. Whatever pattern emerges might be useful for Pawel.
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