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[Cluster-devel] Re: [NFS] [PATCH 0/3] NLM lock failover



James Yarbrough wrote:

take-over server:
B-1. mount the subject filesystem
B-2. "echo 1234 > /proc/fs/nfsd/nlm_set_ip_grace"
B-3. "rpc.statd -n 10.10.1.1 -N -P /shared_storage/sm_10.10.1.1"
B-4. bring up 10.10.1.1
B-5. re-export the filesystem
Umm, don't you want to do B-3 after B-4 and B-5 ?  Otherwise
clients might racily fail on the first try.

I don't think they will necessrily fail.  It depends on whether the
server sends ICMP unreachable messages and how the client responds to
those.  In any case, I think the ordering should be B-5, B-4, and B-3
last.  One can argue about the ordering of B-3 and B-4, but if exporting
(B-5) does not happen before bringing up the IP address (B-4), clients
can get ESTALE replies.  For better transparency, it's probably best
to avoid ESTALE.

It's probably OK to do step B-3 after bringing up the IP address since
that will mimic what happens during boot.

Yes, you and Greg are mostly right - that was an oversight from my test script. But our user mode RHCS script (Lon wrote that piece of code) does it correctly. He did B-5, B-4, and B-3 last.

<info>   Adding export: *:/mnt/tank1 (fsid=9468,rw)
<info>   Adding export: *:/mnt/tank2 (fsid=661,rw)
<debug>  Link for eth0: Detected
<info>   Adding IPv4 address 10.15.89.203 to eth0
<debug>  Sending gratuitous ARP: 10.15.89.203 00:30:48:27:92:d6 brd
ff:ff:ff:ff:ff:ff
<info>   Sending reclaim notifications via tank-02
Start of nfs1 complete

-- Wendy


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