On 2016-09-02 10:09, Ken Gaillot wrote:
On 09/02/2016 08:14 AM, Dan Swartzendruber wrote:
So, I was testing my ZFS dual-head JBOD 2-node cluster. Manual
failovers worked just fine. I then went to try an acid-test by
logging
in to node A and doing 'systemctl stop network'. Sure enough,
pacemaker
told the APC fencing agent to power-cycle node A. The ZFS pool moved
to
node B as expected. As soon as node A was back up, I migrated the
pool/IP back to node A. I *thought* all was okay, until a bit later,
I
did 'zpool status', and saw checksum errors on both sides of several
of
the vdevs. After much digging and poking, the only theory I could
come
up with was that maybe the fencing operation was considered complete
too
quickly? I googled for examples using this, and the best tutorial I
found showed using a power-wait=5, whereas the default seems to be
power-wait=0? (this is CentOS 7, btw...) I changed it to use 5
instead
That's a reasonable theory -- that's why power_wait is available. It
would be nice if there were a page collecting users' experience with
the
ideal power_wait for various devices. Even better if fence-agents used
those values as the defaults.
Ken, thanks. FWIW, this is a Dell Poweredge R905. I have no idea how
long the power supplies in that thing can keep things going when A/C
goes away. Always wary of small sample sizes, but I got filesystem
corruption after 1 fencing event with power_wait=0, and none after 3
fencing events with power_wait=5.
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