High load average mail server 5.3-RELEASE
Eric Anderson
anderson at centtech.com
Fri Sep 23 05:23:20 PDT 2005
Francisco Reyes wrote:
> On Thu, 22 Sep 2005, Eric Anderson wrote:
>
>> Also, if it is an NFS server, one should check the cpu times on the
>> nfsd processes. I've found that many times there aren't enough nfsd
>> processes to take the load from many clients. Increasing the number
>> (double it) often helps this. The max in 5.3 is 20, but you can
>> easily change it and get around it.
>
>
> What is the parameter to change the number of nfsd processes?
Use the -n flag to nfsd, so in /etc/rc.conf:
nfs_server_flags="-u -t -n 1024"
Yep, that's right, I have mine set to 1024. How I got to that number
is simply by watching the cpu time on my nfsd processes. I do this:
ps -auxw | grep nfsd | head -n 20
Which would reveal something like:
root 410 4.2 0.0 1236 732 ?? S 13Sep05 1400:55.70 nfsd:
server (nfsd)
root 411 0.0 0.0 1236 732 ?? S 13Sep05 320:48.27 nfsd:
server (nfsd)
root 409 0.0 0.0 1352 924 ?? Is 13Sep05 0:00.47 nfsd:
master (nfsd)
root 412 0.0 0.0 1236 732 ?? S 13Sep05 83:29.31 nfsd:
server (nfsd)
root 413 0.0 0.0 1236 732 ?? S 13Sep05 39:18.94 nfsd:
server (nfsd)
root 414 0.0 0.0 1236 732 ?? S 13Sep05 25:16.79 nfsd:
server (nfsd)
root 416 0.0 0.0 1236 732 ?? S 13Sep05 19:39.53 nfsd:
server (nfsd)
root 417 0.0 0.0 1236 732 ?? S 13Sep05 15:23.14 nfsd:
server (nfsd)
root 418 0.0 0.0 1236 732 ?? S 13Sep05 13:05.99 nfsd:
server (nfsd)
root 419 0.0 0.0 1236 732 ?? S 13Sep05 11:05.15 nfsd:
server (nfsd)
root 420 0.0 0.0 1236 732 ?? S 13Sep05 9:59.39 nfsd:
server (nfsd)
root 421 0.0 0.0 1236 732 ?? S 13Sep05 8:39.97 nfsd:
server (nfsd)
root 422 0.0 0.0 1236 732 ?? S 13Sep05 7:34.38 nfsd:
server (nfsd)
root 423 0.0 0.0 1236 732 ?? S 13Sep05 6:56.37 nfsd:
server (nfsd)
root 424 0.0 0.0 1236 732 ?? S 13Sep05 6:40.99 nfsd:
server (nfsd)
root 425 0.0 0.0 1236 732 ?? S 13Sep05 6:08.44 nfsd:
server (nfsd)
root 426 0.0 0.0 1236 732 ?? S 13Sep05 5:40.81 nfsd:
server (nfsd)
root 427 0.0 0.0 1236 732 ?? S 13Sep05 6:34.98 nfsd:
server (nfsd)
root 428 0.0 0.0 1236 732 ?? S 13Sep05 4:34.36 nfsd:
server (nfsd)
root 429 0.0 0.0 1236 732 ?? S 13Sep05 3:17.89 nfsd:
server (nfsd)
That's on a very fast box, with a fiber channel connected 16 disk
RAID0+1, with the fastest disks I can buy. Now, with slower disk back
end, you'll probably see something more like this:
root 438 0.0 0.1 1372 964 ?? Is 17Jun05 0:03.14 nfsd:
master (nfsd)
root 439 0.0 0.1 1224 744 ?? S 17Jun05 1010:27.86 nfsd:
server (nfsd)
root 440 0.0 0.1 1224 744 ?? I 17Jun05 231:17.30 nfsd:
server (nfsd)
root 441 0.0 0.1 1224 744 ?? I 17Jun05 125:17.14 nfsd:
server (nfsd)
root 442 0.0 0.1 1224 744 ?? I 17Jun05 76:30.62 nfsd:
server (nfsd)
root 444 0.0 0.1 1224 744 ?? I 17Jun05 94:18.99 nfsd:
server (nfsd)
root 445 0.0 0.1 1224 744 ?? I 17Jun05 54:48.31 nfsd:
server (nfsd)
root 446 0.0 0.1 1224 744 ?? I 17Jun05 63:40.74 nfsd:
server (nfsd)
root 447 0.0 0.1 1224 744 ?? I 17Jun05 38:29.15 nfsd:
server (nfsd)
root 448 0.0 0.1 1224 744 ?? I 17Jun05 46:12.29 nfsd:
server (nfsd)
root 449 0.0 0.1 1224 744 ?? I 17Jun05 15:24.99 nfsd:
server (nfsd)
root 450 0.0 0.1 1224 744 ?? I 17Jun05 13:20.40 nfsd:
server (nfsd)
root 451 0.0 0.1 1224 744 ?? I 17Jun05 28:09.07 nfsd:
server (nfsd)
root 452 0.0 0.1 1224 744 ?? I 17Jun05 11:19.46 nfsd:
server (nfsd)
root 453 0.0 0.1 1224 744 ?? I 17Jun05 19:34.98 nfsd:
server (nfsd)
root 454 0.0 0.1 1224 744 ?? I 17Jun05 9:59.46 nfsd:
server (nfsd)
root 455 0.0 0.1 1224 744 ?? I 17Jun05 8:36.71 nfsd:
server (nfsd)
root 456 0.0 0.1 1224 744 ?? I 17Jun05 7:28.79 nfsd:
server (nfsd)
root 457 0.0 0.1 1224 744 ?? I 17Jun05 6:18.29 nfsd:
server (nfsd)
root 458 0.0 0.1 1224 744 ?? I 17Jun05 5:43.77 nfsd:
server (nfsd)
See how much run time that 20th process has? I like to always have a
couple with zero run time. So I double the number until I get there,
then tune back a little. I've found that a very rough rule of thumb is:
number of nfs clients * 1.8 = nfsd processes
as long as you have the memory for it. You should consider about:
nfsd processes * 2.5MB = memory desired for all the nfsd's
Eric
--
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Eric Anderson Sr. Systems Administrator Centaur Technology
Anything that works is better than anything that doesn't.
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