How to monitor disk io activies using sar?

[zhaogui]

I want to keep track of disk io activities during UAT, but it only shows io on root disks when running sar -d, how can I get the rest?

Thanks,

[Michael Tully]

Hi,

By default 'sar -d' should show all disk devices, as indicated by the man page.

If I run this on my server I get all disks.

# sar -d 5 5

Try also using iostat

# iostat -t 10 5

What OS version and patch level are you using?

Cheers
~Michael~

[Helen French]

Hi,

sar -d will list you the I/O activity in all disks. Not only the root. If you are getting only root disk in the output, that means only root disk is being utilised at that time. Increase the analysis period:

# sar -d 1 20 (for 20 times)
# sar -d 1 30 (for 30 times)

I would suggest you to use GlancePlus (# gpm) for getting a more detailed information.

HTH,
Shiju

[zhaogui]

Thank you for your quick response, now I realise why it only shows root disks, the reason is because of no activity on other disks.

But if I want to analyse the output, how can I do that? I got totally more than 100 disks!

[Michael Tully]

Hi,

If you only have activity on say 5 disks, then the other 95 will be zero. If your trying to monitor disk IO then you should only be worried about disks that have a great number of activity. If they are being thrashed, then you could look at moving some information to disks that are not been thrashed or utilised.

You could use the output from measureware to assist in this. The reporting tools are excellent.

~Michael~

[zhaogui]

Can you elaborate more on these reporting tools?

[U.SivaKumar_2 · Accepted solution]

hi,
#man sar
will give you nessecary details.
By the way , there is a wonderful tool called
sarcheck. www.sarcheck.com . it is a priced product. you can try the evaluation. There are
sample reports in the website.


regards,
U.SivaKumar

[U.SivaKumar_2]

hi,
follow this link.
http://www.hp.com/products1/unix/java/infolibrary/prog_guide/java1_3/measuring_sys_performance.html

regards,
U.SivaKumar