Do I need another PAMii card?

[mdvillanueva]

    Hi Experts,

We have FAS3240 active/active filer, each with SAS and SATA aggregates. Both controllers are currently in 8.1.1. On our SAS, we have Exchange, SQL, Sharepoint and NFS datastores for VM. We also have a PAMii card on each controller.

Our Exchange server(2007, OS is a VM, iscsi luns for the dbs and logs) latency goes up (as detected by Windows perfmon) most of the time when a vmotion is happening in the VM environment. I monitor latency of LUNS and the containing volumes but normally they won't spike up.

It is really hard to figure out if it is the Exchange, or the VM environment or Netapp storage. I am wondering if we are using our Pamii properly.

Here is how it is configured right now.

flexscale.enable           on

flexscale.lopri_blocks     on

flexscale.normal_data_blocks     on    

flexscale.pcs_high_res     off

flexscale.pcs_size        0GB

flexscale.rewarm     on

If we need another Pamii, i want to figure out what numbers I can look at so I can justify it.

Thanks,

[scottgelb]

Any specific reason for Lopri? That caches writes. Used when you know you read back what is written.

[mdvillanueva]

Hi Scott,

I honestly don’t know why that is turned on or if the consultant who installed our Netapp environment did that on purpose?

Is that on or off by default? Also, is there any benefit for using that, lets say for Exchange or VM environment?

Will changing that option be non-disruptive and will take effect immediately?

Thank you!

Maico

[scottgelb]

Non disruptive to change. But ask why it was set. Not a default but they may have had Analytics showing it would help. It may cause higher evicts of no read after wrote and would typically see it off. Is it the same on both nodes?

Sent from my iPhone 5

[mdvillanueva]

Yes it is the same on both node. However on our other active/active pair both filers have that option off. I will inquire with them. Thanks for the advise.

Maico

[mdvillanueva]

Scott, what do you mean when you said it may cause higher evicts? I can see right now that the evicts are in the 100-300 range.

on the filer that has that disabled, the evicts is 0

[scottgelb]

Evicts when invalidated or pushed out.

Sent from my iPhone 5

[mdvillanueva]

this is the kind of stat I see

Cache Reads Writes Disk Reads

Usage Hit Meta Miss Hit Evict Inval Insert Chain Blocks Chain Blocks Replaced

% /s /s /s % /s /s /s /s /s /s /s /s

98 1273 906 6764 15 105 5920 4990 1029 1248 77 4990 1029

98 3024 185 6162 32 111 1982 3833 479 2993 59 3823 479

98 12372 560 6734 64 297 11645 9667 1748 12292 151 9666 1748

98 5317 862 6132 46 256 7896 7671 1241 5222 120 7680 1241

98 1196 546 5906 16 239 7939 8252 705 1174 129 8257 705

98 414 142 6108 6 0 0 0 253 397 0 0 253

98 2559 643 6573 28 201 4246 5245 1240 2508 81 5246 1240

98 550 179 9793 5 447 7981 8182 332 522 127 8173 332

98 1339 1100 5178 20 436 11840 14188 1176 1315 221 14188 1176

98 1214 725 6073 16 282 15760 12922 878 1173 201 12921 878

98 844 161 7628 9 59 0 2752 345 809 42 2751 345

98 1271 865 6646 16 230 12193 10826 1081 1264 169 10829 1081

98 1268 694 5575 18 90 8093 6823 904 1216 106 6830 904

98 1025 570 6491 13 129 3471 5790 770 997 90 5790 770

98 1149 422 5511 17 168 12461 12143 658 1036 189 12140 658

98 1623 473 6592 19 204 7969 9857 814 1458 153 9853 814

98 678 224 6122 9 24 3353 822 414 644 12 831 414

98 8395 502 5191 61 269 7943 10473 1414 8271 163 10458 1414

98 4163 456 5356 43 142 7938 7759 1037 4136 121 7774 1037

98 1561 779 7265 17 209 7784 8154 1067 1461 127 8149 1067

98 758 185 6467 10 91 4932 3140 438 717 48 3134 438

98 1462 425 5144 22 313 7897 9457 799 1453 147 9453 799

98 1910 1348 7193 20 93 7908 6210 1565 1850 97 6222 1565

[scottgelb]

Worth talking to your consultant ad possibly test turning off Lopri. Then wait at least a day and compare cache hit rates.

[mdvillanueva]

What set of data normally is a good option to be running in low-priority mode?

[scottgelb]

Tr3832 gives a great overview. Lopri to cache data that is written to disk but not cached after. So that recent written data has a higher priority in memory instead of on disk for the next reads.

Sent from my iPhone 5

[mdvillanueva]

I am curious if in Exchange environment is one of those application that benefits from low-priority mode. I wish someone knows.

[scottgelb]

TR-3867 Using Flash Cache for Exchange 2010 ..