ZFS: Failed pool causes system to hang
Quartz
quartz at sneakertech.com
Thu Mar 21 17:22:47 UTC 2013
So looking through the past couple emails, it doesn't appear that anyone
included a complete copy of my description when CCing -fs, so I'm going
to do that now just so there's no confusion. I'll respond to Jeremy's
questions separately.
------
I have a raidz2 comprised of six sata drives connected via my
motherboard's intel southbridge sata ports. All of the bios raid options
are disabled and the drives are in straight ahci mode (hotswap enabled).
The system (accounts, home dir, etc) is installed on a separate 7th
drive formatted as normal ufs, connected to a separate non-intel
motherboard port.
As part of my initial stress testing, I'm simulating failures by popping
the sata cable to various drives in the 6x pool. If I pop two drives,
the pool goes into 'degraded' mode and everything works as expected. I
can zero and replace the drives, etc, no problem. However, when I pop a
third drive, the machine becomes VERY unstable. I can nose around the
boot drive just fine, but anything involving i/o that so much as sneezes
in the general direction of the pool hangs the machine. Once this
happens I can log in via ssh, but that's pretty much it. I've
reinstalled and tested this over a dozen times, and it's perfectly
repeatable:
`ls` the dir where the pool is mounted? hang.
I'm already in the dir, and try to `cd` back to my home dir? hang.
zpool destroy? hang.
zpool replace? hang.
zpool history? hang.
shutdown -r now? gets halfway through, then hang.
reboot -q? same as shutdown.
The machine never recovers (at least, not inside 35 minutes, which is
the most I'm willing to wait). Reconnecting the drives has no effect. My
only option is to hard reset the machine with the front panel button.
Googling for info suggested I try changing the pool's "failmode" setting
from "wait" to "continue", but that doesn't appear to make any
difference. For reference, this is a virgin 9.1-release installed off
the dvd image with no ports or packages or any extra anything.
I don't think I'm doing anything wrong procedure wise. I fully
understand and accept that a raidz2 with three dead drives is toast, but
I will NOT accept having it take down the rest of the machine with it.
As it stands, I can't even reliably look at what state the pool is in. I
can't even nuke the pool and start over without taking the whole machine
offline.
______________________________________
it has a certain smooth-brained appeal
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