Am 18.02.16 um 21:57 schrieb Schweiss, Chip:
On Thu, Feb 18, 2016 at 5:14 AM, Michael Rasmussen <m...@miras.org
<mailto:m...@miras.org>> wrote:
On Thu, 18 Feb 2016 07:13:36 +0100
Stephan Budach <stephan.bud...@jvm.de
<mailto:stephan.bud...@jvm.de>> wrote:
>
> So, when I issue a simple ls -l on the folder of the vdisks,
while the switchover is happening, the command somtimes comcludes
in 18 to 20 seconds, but sometime ls will just sit there for minutes.
>
This is a known limitation in NFS. NFS was never intended to be
clustered so what you experience is the NFS process on the client side
keeps kernel locks for the now unavailable NFS server and any request
to the process hangs waiting for these locks to be resolved. This can
be compared to a situation where you hot-swap a drive in the pool
without notifying the pool.
Only way to resolve this is to forcefully kill all NFS client
processes
and the restart the NFS client.
I've been running RSF-1 on OmniOS since about r151008. All my clients
have always been NFSv3 and NFSv4.
My memory is a bit fuzzy, but when I first started testing RSF-1,
OmniOS still had the Sun lock manager which was later replaced with
the BSD lock manager. This has had many difficulties.
I do remember that fail overs when I first started with RSF-1 never
had these stalls, I believe this was because the lock state was stored
in the pool and the server taking over the pool would inherit that
state too. That state is now lost when a pool is imported with the
BSD lock manager.
When I did testing I would do both full speed reading and writing to
the pool and force fail overs, both by command line and by killing
power on the active server. Never did I have a fail over take more
than about 30 seconds for NFS to fully resume data flow.
Others who know more about the BSD lock manager vs the old Sun lock
manager may be able to tell us more. I'd also be curious if Nexenta
has addressed this.
-Chip
I actually don't know, if it's the lock manager or the nfsd itself, that
caused this, but as I bounced all of them after I failed the ZPOOL over
while hammering it with reads and writes, lockd would also have been
part of the processes that had been restarted. And remeber, this only
happend when failing from to and back one host in a rather quick manner.
Nevertheless, RSF-1 seems to be a solid solution and I will very likely
implement it across several OmniOS boxes.
Cheers,
Stephan
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