I read that, unfortunately I am not at 7.3.2 yet, I do get the counters but the format is a bit old.
 
My disk utilization rarely goes above 25%
 
Here's what I see but since I'm not at 7.3.2 the numbers may be misleading, I don't know.
array01*> stats show -p flexscale-pcs
Instance    Blocks Usage   Hit  Miss Hit Evict Invalidate Insert
---
     ec0   4194304    90 11733  3479  77  1748         57   2236
     ec1   4194304    38  1203  2275  34   343        401   1748
     ec2   8388608     2    95  2180   4     0         39    343
---
     ec0   4194304    90  7225  3306  68   430        140    548
     ec1   4194304    38   756  2550  22    82        130    430
     ec2   8388608     2    62  2487   2     0         15     82
---
     ec0   4194304    90  8683  4467  66   422          0    554
     ec1   4194304    38  1325  3142  29    71         74    422
     ec2   8388608     2   129  3012   4     0          6     71
---
     ec0   4194304    90  7965  4485  63  2300        122   2940
     ec1   4194304    38  1497  2988  33   415        528   2300
     ec2   8388608     2   167  2821   5     0         47    415
---
     ec0   4194304    90  4996  4661  51  1793         54   2346
     ec1   4194304    38  1114  3547  23   316        328   1793
     ec2   8388608     2   116  3431   3     0         25    316
---
     ec0   4194304    90  6915  4437  60   875          0   1141
     ec1   4194304    38  1725  2712  38   168        124    875
     ec2   8388608     2   201  2511   7     0         10    168
From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Romeo Theriault
Sent: Monday, February 22, 2010 9:13 AM
To: Page, Jeremy
Cc: toasters@mathworks.com
Subject: Re: PAM cards or disks and some questions about the impact of running with PAM

Hi Jeremy, You may want to take a look at this webpage:

http://ctistrategy.com/2009/02/27/netapp-cache-pcs/

talks about how to gauge some of these items you're looking at. OnTap (I believe it only starts in 7.3.2 though) has a new option called Predictive Cache Statistics that you can use to monitor and help you predict if a PAM card would be helpful for you.

Here are some other things that might be worth looking at too.

  * What is your disk utilization look like?  (sysstat -x 3   or you can get a closer look with statit )
  * What is your cache age? If this is really low I think a pam card could help.


Will be interested in what you eventually decide as I think we'll be looking into using a PAM card in the future.

Romeo

On Mon, Feb 22, 2010 at 10:35 PM, Page, Jeremy <jeremy.page@gilbarco.com> wrote:
I apologize that this is so long but it's kind of complicated and I don't want to blow my budget on the wrong stuff.
 
I've got a mixed use 3070A at 7.3.1P2D11 hosting FC based AIX boxes (about 4k IOPS average, 90+% reads), 300 or so VMs (NFS, 3k IOPS average) and 1,000 users home/departmental shares via CIFS and NFS (2500 IOPS on a busy day. Oracle is starting to get a bit pokey and I've budgeted for some upgrades this coming quarter. The question is should I be buying spindles or PAM cards. Currently this load is spread across 231 spindles in wide stripes (minimum 12 disks per RG). So not great performance but it also takes a big spike to have a major negative impact as well. 
 
I have good performance metrics for everything except Oracle, which for some reason is seeing poor performance even though latency and throughput look good. Of course there is no DBA running this database so I suspect at least part of the problem is on the Oracle side but for now I have to assume that's not going to improve. Currently we are already observing a very good cache hit % so I am questioning if the PAM cards will give any benefit there. On the other hand statit shows that 2/3 of the IO from disk is still reads so I think maybe there would be a benefit and I know it would be great for file shares & VMs (which are also on deduped volumes so it's my understanding the cache from the PAM cards would be even more effective).
  • How do I determine what to purchase?
  • What's does the "seek time" for data read from PAM?
  • I'm getting to the point where the 3070 is going to work really hard in a fail over situation, if PAM cards can service a lot more requests in a short period if the data is cached on SSD will this put more load on my CPUs?
  • Why did NetApp name them Pam? It's not the 60's, they should be named Shelby or Logan cards or something?

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--
Romeo Theriault
System Administrator
Information Technology Services