Writing over NFS causes lots of paging

From: Simon Kirby (sim@netnation.com)
Date: Sun Nov 11 2001 - 05:48:55 EST


It looks like when writing large amounts of data to NFS where the remote
end is slower than the local end the local end appears to start swapping
out a lot I'm guessing this is because it can read much faster than it
can write.

Also, I see NFS timeouts and thus "I/O error" messages fom cp when it is
mounted with the "soft" option, even with high timeouts. "hard" works
fine, but I didn't want to use it for this mount.

For example:

procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
0 0 0 70316 4128 608 141744 0 0 4172 0 3065 4214 1 12 87
0 0 0 70316 3156 620 142704 0 92 3896 92 2904 4028 1 11 88
0 1 0 70316 4208 672 141604 0 40 2912 40 3248 4715 2 12 86
1 0 0 70316 3228 724 142528 0 296 3284 296 2904 4682 5 17 79
0 1 0 70700 4048 720 141948 0 124 3744 124 2987 4109 1 14 85
1 1 0 70700 3752 724 142376 0 116 4136 116 2927 3985 1 16 83
1 0 0 70956 3816 712 142384 0 180 3964 180 2724 3801 1 15 84
0 0 0 70956 3968 720 142308 0 0 3908 0 3045 4277 2 13 84
0 1 0 71724 3336 724 142984 0 580 3796 580 2837 4985 9 21 69
0 0 0 71724 3924 736 144116 0 588 3776 588 2860 3950 1 14 85
0 1 0 72236 3120 752 146132 0 556 3380 556 2731 3983 1 9 89
0 0 0 73260 3212 752 146140 0 2496 3468 2496 2516 3637 1 14 85
0 0 0 73900 3476 744 145868 0 640 3900 640 2776 3888 0 13 87
0 0 0 74156 3192 736 146212 0 540 4150 540 2916 4010 1 15 83

The copy is still running and almost everything is swapped out now
(140 MB). When the copy started, there was about 30 MB of swap.

NFS client (reading from disk and writing through NFS): 2.4.15pre1
NFS server (writing to disk from NFS): 2.4.15pre2
NFSv3 and knfsd used.

Is there something different with the VM here? Should I try 2.4.15pre2
on the NFS client?

Simon-

[ Stormix Technologies Inc. ][ NetNation Communications Inc. ]
[ sim@stormix.com ][ sim@netnation.com ]
[ Opinions expressed are not necessarily those of my employers. ]
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This archive was generated by hypermail 2b29 : Thu Nov 15 2001 - 21:00:26 EST