"Server not responding" after periods of client inactivity
Subsystems (2)
(Trying to post this for the third time -- nothing appeared on the list the first two times.)
I have noticed that after periods of inactivity on the client machine, the first NFS operation will always hang for around 15 seconds. My first guess was that the server had powered down its disk drives, and that it was the spin-up time that caused the delay, but when I had an ssh session open on the server at the same time as the client started complaining about not getting a reply, I saw that this was /not/ the case -- there is nothing on the server that would explain why the client is stalling. No load, and no delay when working directly on the server.
I did tcpdump (on the server side) while the client was hanging, and this is what I found:
Source Time Packets ------ ---- ------- client 0.00 V3 ACCESS Call, FH:0x02120000 client 0.10 [Retransmission of #1] V3 ACCESS Call, FH:0x02120000 client 0.31 [Retransmission of #1] V3 ACCESS Call, FH:0x02120000 client 0.71 [Retransmission of #1] V3 ACCESS Call, FH:0x02120000 client 1.53 [Retransmission of #1] V3 ACCESS Call, FH:0x02120000 client 3.16 [Retransmission of #1] V3 ACCESS Call, FH:0x02120000 client 6.42 [Retransmission of #1] V3 ACCESS Call, FH:0x02120000 client 7.12 [Retransmission of #1] V3 ACCESS Call, FH:0x02120000 client 8.52 [Retransmission of #1] V3 ACCESS Call, FH:0x02120000 client 11.32 [Retransmission of #1] V3 ACCESS Call, FH:0x02120000 server 15.30 V3 ACCESS Reply
After this, there are no more delays for this shared file system; any file operation on the same file system will succeed instantly. However, the first operation on any /other/ NFS file system also mounted on the client will still hang just like the above example. I.e., the hang always happens exactly once for each mount point.
I have tried setting rsize=1024,wsize=1024, and I have tried both tcp and udp, but nothing has helped so far. Any ideas? tcpdump clearly shows that all the requests arrive at the server, so why does the server wait 15 seconds before it replies?
NFS server:
Pentium III 650 MHz, 256 MB RAM
Fedora Core 3 (fully updated)
nfs-utils 1.0.6-52
kernel 2.6.11-1.35_FC3
NFS client:
Athlon XP2500+, 1 GB RAM
Slackware 10.1
nfs-utils 1.0.7
kernel 2.6.11.11
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