It might also be helpful to know how many disks are in the raid group. 2? 10? Apologies if it was mentioned earlier. How much NVRAM?
Jason
-----Original Message----- From: Kumar, Rahul [mailto:Rahul.Kumar@sdrc.com] Sent: Wednesday, February 06, 2002 12:48 PM To: Chris Thompson; Mike Ball; Edward Hibbert Cc: toasters@mathworks.com Subject: RE: Slow write performance
Hi All, I think in this case if he could use
sysstat -x 1 he would get a output kinda like this which might help diaganosing further... filer1> sysstat -x 1 CPU NFS CIFS HTTP Total Net kB/s Disk kB/s Tape kB/s Cache Cache CP CP Disk in out read write read write age hit time ty util 2% 55 12 0 67 19 21 24 0 0 0 >60 99% 0% - 2% 8% 150 9 0 159 31 33 112 1309 0 0 >60 100% 15% T 15% 1% 21 4 0 25 28 30 0 0 0 0 >60 100% 0% - 0% 3% 132 0 0 132 1 1 0 0 0 0 >60 100% 0% - 0% 4% 97 71 0 168 26 30 0 0 0 0 >60 100% 0% - 0% 2% 91 0 0 91 36 21 0 0 0 0 >60 100% 0% - 0% 2% 57 20 0 77 14 17 32 0 0 0 >60 96% 0% - 4% 4% 172 10 0 182 31 33 0 0 0 0 >60 100% 0% - 0% 1% 18 4 0 22 31 33 0 0 0 0 >60 100% 0% - 0% filer1> ----------- Rahul Kumar EDS PLM Solutions - EIT (Pune-India) Rahul.Kumar@sdrc.com Work: 91-20-2930812
-----Original Message----- From: Chris Thompson [mailto:cet1@cus.cam.ac.uk] Sent: Wednesday, February 06, 2002 9:26 PM To: Mike Ball; Edward Hibbert Cc: toasters@mathworks.com Subject: Re: Slow write performance
MBall@datalink.com (Mike Ball) writes
I not sure I would be concerned about the 0's on disk writes you
are
seeing. As long as Net KB keeps coming in/out. The Netapp may be recalculating parity and holding the writes in NVRAM before it flushes
to
disk, etc..
He should be worried about there being too *few* 0's! As anyone who has done a "sysstat 1" (or just watched the pretty lights on the discs :-]) knows, ONTAP does disk writes in bursts (CPs). It will do a CP about once every 11 seconds unless NVRAM gets half-full (or some other exceptional condition happens) first.
Edward's CP's seem to be taking about 5-6 seconds each: that's definitely not normal. If he could do "sysstat -u" (presumably the reason he can't is that he is still on ONTAP 5.x), then he would see something like 50% in the "CP time" column. The cache age being stuck down at 1 minute all the time doesn't look healthy either.
It may be that the disc read traffic is what is making the CPs take so long. That's an effect I have observed during dumps when obviously there is a lot of read traffic, but the CP-expansion is not usually as extreme as in this case.
Chris Thompson University of Cambridge Computing Service, Email: cet1@ucs.cam.ac.uk New Museums Site, Cambridge CB2 3QH, Phone: +44 1223 334715 United Kingdom.