On Tue, 12 May 2009 22:10:58 -0400
Rince <rincebr...@gmail.com> wrote:

> Hi world,
> I have a 10-disk RAID-Z2 system with 4 GB of DDR2 RAM and a 3 GHz Core 2 Duo.
> 
> It's exporting ~280 filesystems over NFS to about half a dozen machines.
> 
> Under some loads (in particular, any attempts to rsync between another
> machine and this one over SSH), the machine's load average sometimes
> goes insane (27+), and it appears to all be in kernel-land (as nothing
> in userland reports more than 5% CPU usage, and top reports 50%+ CPU
> usage).
> 
> I say 27+ because when the load spikes this high, the machine stops
> responding to any meaningful commands. Console login will take a
> username and password then hang forever without printing anything. SSH
> login will block forever without prompting for user or password.
> Machine responds to ping. NFS drops.
> 
> snv_113, this has occurred since the RAID-Z2 was created (b102).
> 
> I have no idea how to instrument this, as it doesn't appear to be
> panicking, or running out of RAM (as far as I can see from the last
> responses of top and prstat), and I don't know how to ask dtrace about
> where I'm mostly spending my time. I read one or two guides, but I
> don't follow how the output of it is meaningful.
> 
> I'm sending this to zfs-discuss as I can't replicate this problem
> unless I'm doing heavy I/O on ZFS.
> 
> (Final note - this 10-disk pool is serviced by an ARC 1280ML, and
> during the time the kernel is  heavily under load, zpool iostat -v is
> reporting no more than 1 MB/s per disk, and almost always to the tune
> of 128 KB/s.)


Ah, this last snippet of information is interesting
(to me at least, since I integrated the arcmsr driver).

Is the ARC1280ML in raid or jbod mode? Are you using the
Sun-supplied arcmsr(7d), or the Areca version?

You might want to try running the attached D script, dumping the
output to a file.



James C. McPherson
--
Senior Kernel Software Engineer, Solaris
Sun Microsystems
http://blogs.sun.com/jmcp       http://www.jmcp.homeunix.com/blog
Kernel Conference Australia - http://au.sun.com/sunnews/events/2009/kernel

Attachment: arcmsr.d.all
Description: Binary data

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