I/O performance on vxvm disks

[shiv124]

HI ,

we are seeing high i/o wait on one of our VCS server .

How to check the I/O  bottle neck issues on VXXM devices ?

What values we need to check ?

When we use iostat -x command .we observe  VxVM OS devices .How to check to which veritas disk this mapped ?

Regards,

siva

[Gaurav_S]

Hi Siva,

you have multiple options ...

1. you can use vxstat utility to find details of IO on vxvm devices ...

refer

http://sfdoccentral.symantec.com/sf/4.1/solaris64/manpages/vxvm/vxstat_1m.html

2. If you want to know details path wise & if you are using DMP, you can use vxdmpadm iostat to collect statistics of DMP devices

refer

http://sfdoccentral.symantec.com/sf/5.0/solaris64/html/vxvm_admin/ag_ch_dmp_vm23.html

3. You can look for "FirstLook" utility from Symantec which helps collect lot of these statistics & helps Symantec support to analyze the same ..

To answer your last question, to know what device a volume maps to you need to use

# vxprint -htg <diskgroup> <volume>    (this will print details of volume, look for line starting with "sd" to know the disk in use for that volume)

# vxdisk -e list (this command can help to map OS device names with vxvm disk names)

hope this helps

G

[shiv124]

hi Gaurav ,

Thanks for the reply

In Linux when we use iostat i see vxvm devices named in this way.I need to findout to which vxvm disk these devices would be mapped.

Vxprint -ht would not give the device naming in this way "VxVM27000 ". i didnt checked when i am replying so i may be wrong

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util

VxVM27000 0.04 0.00 0.14 0.92 39.14 14.39 50.73 0.00 2.85 2.44 0.26

VxVM27001 0.04 0.00 0.19 0.73 39.19 11.90 55.97 0.00 2.07 2.01 0.18

VxVM10000 0.02 0.00 0.02 0.68 0.86 11.27 17.17 0.00 1.34 1.28 0.09

VxVM10001 0.02 0.00 0.02 0.00 0.17 0.00 9.17 0.00 10.79 10.77 0.02

VxVM4000 0.02 0.00 0.02 0.02 1.72 1.67 83.76 0.00 25.78 7.13 0.03

VxVM4001 0.02 0.00 0.07 0.19 2.11 2.30 17.08 0.00 3.66 3.04 0.08

siva

[Gaurav_S · Accepted solution]

Did you try using "vxdisk -e list" to map your disks with OS name  ?

G

[shiv124]

HI Gavrav ,

I got this info.It is the minor number of the devices from /dev/vx/dsk.

thanks

siva