Understanding Sar Reports

[Briwood]

I am trying to troubleshoot a hot disk issue on one of my Solaris 10 servers; sar reporting is turned on and gathering data. This server also uses Veritas Volume Manager and have determind that vol26 is performing poorly in our backup application. I know this because the backup admin says that when vol26 is being used, backups to disk are very slow. If he pulls that volume out, it's very fast. I would like to equate that Veritas Volume to the physical disk in the sar report. These are the steps I'm trying...

Step 1
[rchaxp05:root / ] # vxprint|grep vol26
v tsm_pool_vol26 fsgen ENABLED 134205440 - ACTIVE - -
pl tsm_pool_vol26-01 tsm_pool_vol26 ENABLED 134205440 - ACTIVE - -
sd tsm_pool_disk26-01 tsm_pool_vol26-01 ENABLED 134205440 0 - - -

Step 2
[rchaxp05:root / ] # vxdisk list|grep tsm_pool_disk26
c7t18d33s2 auto:cdsdisk tsm_pool_disk26 tsm_pool_dg online

Step 3
[rchaxp05:root / ] # ls -l /dev/dsk|grep c7t18d33s2
lrwxrwxrwx 1 root root 44 Feb 2 13:36 c7t18d33s2 -> ../../devices/pci@8,600000/lpfc@1/sd@12,21:c

Step 4
[rchaxp05:root / ] # grep sd@12,21 /etc/path_to_inst
"/pci@8,600000/lpfc@1/sd@12,21" 185 "sd"


Sample of the sar report
00:00:00
device %busy avque r+w/s blks/s avwait avserv
sd185 0 0.0 0 0 0.0 0.0
sd185,c 0 0.0 0 0 0.0 0.0
sd185,h 0 0.0 0 0 0.0 0.0



I was thinking that sd185 was the device that I should be looking at, but all throughout the sar report there is no activity on sd185, when suspected busy and not.

Am I reading this wrong? Your assistance is appreciated.

Brian

 

[Annihilannic]

Your logic looks sound to me.

How about using vxstat -vdg diskgroup -i 5 while the disks and volume are supposedly busy and see what the results are?

Annihilannic.

 

[Briwood]

Annihilannic-

Thank you for the vx command. This will definitely help when troubleshooting a current disk performance issue.

I was also hoping to see if there was a trend with issue on the same disk, which was why I was looking at the sar report. I found a pretty cool java program (Ksar) that I can run on my PC to view the sar reports in graph format. Pretty slick.

Brian