There could be several reasons why the #s don't always match
1) All of this is sampling over time. So if you take a "snapshot" of the stats over a given second or few seconds, there could be I/Os left over from the previous interval or coming into play. 2) WAFL could be doing read-aheads to try and get more info in cache. So you ask for a certain size read, and the filer intentionally pulls more to try and pull more into the read cache. 3) In general, I throw out the first sample from sysstat, which is the example you are using. It's usually off, probably again due to getting the sampling up and running. Most of the rest of your output doesn't show quite the same disparity.
There could be other reasons as well, but these are off the top of my head.
-- Adam Fox adamfox@netapp.com
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From: owner-dl-toasters@jhereg.corp.netapp.com [mailto:owner-dl-toasters@jhereg.corp.netapp.com] On Behalf Of Li, Jackie (Yanhui) Sent: Tuesday, February 20, 2007 1:55 PM To: toasters@mathworks.com Subject: sysstat question:
I have a 3020 filers running 7.1.1, I am confuse by the sysstat:
Disk KB/s is 20MB/s, while FCP(no NFS) is doing 9MB/s, how big is the disk strip size 64KB, I am guessing disk is always IOs at strip size.
Also the FCP IO number is 581 IO/s , and I used statsit command to collect disk usage, it showed there are 23 disks are doing 55 IO/s, so total disk is doing 1265 IO/s, does anybody know why backend disk are doing more IOs than FCP?
Thanks
CPU NFS CIFS HTTP Total Net kB/s Disk kB/s Tape kB/s Cache Cache CP CP Disk FCP iSCSI FCP kB/s
in out read write read write age hit time ty util in out
9% 0 0 0 581 1 2 20120 16 0 0 2 98% 0% - 13% 581 0 67 9261
3% 0 0 0 135 0 0 2584 12 0 0 2 95% 0% - 9% 134 0 290 1844
2% 0 0 0 121 0 0 2064 4 0 0 2 95% 0% - 20% 121 0 509 1566
5% 0 0 0 146 0 0 5161 2503 0 0 2 96% 23% T 12% 146 0 255 2053
3% 0 0 0 185 0 0 3404 12 0 0 2 95% 0% - 12% 185 0 136 2499
8% 0 0 0 694 0 0 5694 4 0 0 2 98% 0% - 15% 694 0 2982 3724
9% 0 0 0 400 1 1 18294 12 0 0 2 98% 0% - 18% 400 0 792 11466
6% 0 0 0 306 0 0 12856 16 0 0 2 97% 0% - 25% 306 0 550 7419
7% 0 0 0 242 1 1 6905 4482 0 0 3 96% 28% T 21% 242 0 366 3709
2% 0 0 0 127 0 0 2476 12 0 0 3 95% 0% - 9% 127 0 38 1889
2% 0 0 0 120 1 1 2348 16 0 0 3 96% 0% - 11% 120 0 128 1697
3% 0 0 0 156 0 0 4476 0 0 0 3 96% 0% - 14% 156 0 272 2486
4% 0 0 0 214 1 2 4084 16 0 0 3 95% 0% - 16% 214 0 773 2608
5% 0 0 0 183 1 1 5228 2890 0 0 3 95% 21% Tf 29% 183 0 264 2407
4% 0 0 0 209 7 18 3952 16 0 0 3 95% 2% : 16% 209 0 9 3026
7% 0 0 0 462 0 0 12176 16 0 0 3 97% 0% - 20% 462 0 484 6376
Jackie(Yanhui) Li
Global Infrastructure Services
Electronic Arts
650-6285746