Re: Mysterious Lag With SATA Maxtor 250GB 7200RPM 16MB Cache Under Linux using NFSv3 UDP

[Norbert van Nobelen]

Only with NFS? I have a raid array of the same discs and the system just 
sometimes seems to hang completely (for a second or less) and then to go on 
again at a normal speed (110MB/s).
I am running a SuSE 9.1 stock kernel (2.6.5-7.111-smp) on that machine.

On Monday 17 January 2005 21:06, you wrote:
> When writing to or from the drive via NFS, after 1GB or 2GB, it "feels"
> like the system slows to a crawl, the mouse gets very slow, almost like
> one is burning a CD at 52X under PIO mode.  I originally had this disk in
> my main system with an Intel ICH5 chipset (ABIT IC7-G mobo) and a Pentium
> 4 2.6GHZ w/HT and I could not believe the hit the system took when writing
> over NFS.
>
> I put the drive on its own controller in another box to see if I could
> replicate the problem.  The drive is on a Promise 150TX2 Plus controller.
> When writing locally on the disk, there is no problem.  When writing to or
> from the drive over NFS, the system becomes _very_ slow, df -h lags, the
> system slows almost to a halt.  I check /proc/interrupts and
> /var/log/messages but no errors result.
>
> There is some type of system bottleneck when using NFS with this drive.
>
> All the file systems are XFS on all systems.
> Can anyone offer any suggestions?
> I cannot explain or find the cause of this.
>
> All systems are running 2.6.10.
>
> I have an excerpt of both using dd if=/dev/zero of=file.img (locally) and
> from a remote computer (on a full duplex gigabit network)
>
> Locally: dd if=/dev/zero of=out.img
>
> vmstat output:
>
> procs -----------memory---------- ---swap-- -----io---- --system--
> ----cpu----
>   r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy
> id wa
>   1  0    412   4928      0 662612    0    0     0     0 1065   285 16 84
> 0  0
>   1  0    412   4608      0 662556    0    0     0 78932 1148   250 14 86
> 0  0
>   1  0    412   4672      0 662868    0    0     0    13 1068   274 16 84
> 0  0
>   1  0    412   5120      0 661644    0    0     0 78928 1116   245 13 87
> 0  0
>   1  0    412   4460      0 663020    0    0     0     0 1098   254 15 85
> 0  0
>   1  0    412   5376      0 660936    0    0     0 78932 1073   279 14 86
> 0  0
>   1  0    412   5376      0 662124    0    0     0    17 1147   267 18 82
> 0  0
>   2  0    412   5376      0 661580    0    0    44 31901 1052   286 15 85
> 0  0
>   1  0    412   5440      0 661740    0    0    48 47048 1168   265 15 85
> 0  0
>   1  0    412   5312      0 662152    0    0     4    14 1048   260 16 84
> 0  0
>   1  0    412   4664      0 662196    0    0     4 78941 1143   282 15 85
> 0  0
>   2  0    412   4600      0 662932    0    0     0     0 1104   251 14 86
> 0  0
>   1  0    412   5048      0 661448    0    0     0 78954 1111   269 16 84
> 0  0
>   1  0    412   5368      0 662120    0    0     0     0 1140   250 17 83
> 0  0
>   1  0    412   5432      0 660648    0    0     0 78928 1075   260 16 84
> 0  0
>   1  0    412   5176      0 662224    0    0     4     0 1217   266 14 86
> 0  0
>   1  0    412   5432      0 662104    0    0     0     0 1078   274 16 84
> 0  0
>   1  0    412   4984      0 662084    0    0     0 78932 1189   245 12 88
> 0  0
>   1  0    412   5440      0 662012    0    0     0    13 1080   271 17 83
> 0  0
>   1  0    412   5440      0 661168    0    0     0 78928 1109   242 14 86
> 0  0
>   1  0    412   5248      0 662232    0    0     0     0 1104   270 13 87
> 0  0
>
> Remotely (writing over NFS, using NFS v3, not using direct I/O)
>
> vmstat output:
>
> procs -----------memory---------- ---swap-- -----io---- --system--
> ----cpu----
>   r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy
> id wa
>   1  0    596   4624      0 662460    0    0     0   448 4037  1099  1 99
> 0  0
>   1  0    596   4796      0 661564    0    0     0 96067 2877   788  1 75
> 0 24
>   0  0    596   5496      0 661692    0    0     0   160 2297   517  0 44
> 56  0
>   1  0    596   4824      0 662840    0    0    24   633 3896  1147  1 98
> 1  0
>   1  0    596   4696      0 662536    0    0     0   416 3987  1075  1 99
> 0  0
>   1  0    596   4892      0 662344    0    0     0   448 3746  1142  0 99
> 1  0
>   0  0    596   5868      0 660468    0    0     0 96064 3550   973  1 97
> 1  1
>   2  0    596   4600      0 663328    0    0     0   318 3390   823  1 71
> 28  0
>   1  0    596   5432      0 662336    0    0     0   448 3872  1066  0 100
> 0  0
>   1  0    596   5360      0 661888    0    0     0   453 3951  1144  1 99
> 0  0
>   1  0    596   4936      0 661568    0    0     0 94225 2942   726  0 75
> 7 18
>   1  0    596   4528      0 662944    0    0     0   259 2984   738  1 64
> 35  0
>   1  0    596   5368      0 661864    0    0     8   639 4234  1116  1 99
> 0  0
>   2  0    596   5368      0 662140    0    0     0   448 3919  1086  0 100
> 0  0
>   0  0    596   5512      0 662860    0    0     4   256 2747   650  0 56
> 43  1
>   0  0    596   5520      0 662860    0    0     0     0 1061   144  3  2
> 95  0
>   1  0    596   4688      0 663404    0    0     0    64 1455   312  0 13
> 87  0
>   1  0    596   5324      0 661964   32    0    40 96489 3325   921  1 88
> 11  0
>   1  0    596   4656      0 662852   24    0   144  1093 2228   650  1 38
> 58  3
>   1  0    596   4592      0 662648    0    0     0   448 3852  1098  0 99
> 1  0
>   1  0    596   5304      0 662232    0    0     0   448 3972  1100  1 99
> 0  0
>
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