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Capturing Disk write data

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Mohanasundaram_1
Honored Contributor

Capturing Disk write data

Hi Folks,

I wanted to capture the disk writes (Kb/s) information in a system with multiple LUNs. The system utilities sar and iostat provides the read+write together and I am unable to find a way to capture the write data specifically.

Is there a way to do it? If I have glance can I collect such data over a period of 24hours? What is the command options using glance to capture only the disk writes.

As usual the relevant answers will get points.

With regards,
Mohan.
Attitude, Not aptitude, determines your altitude
7 REPLIES
Hakki Aydin Ucar
Honored Contributor

Re: Capturing Disk write data

Only solution seems to use Glance for this

also check this out:
http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1165546
Duncan Edmonstone
Honored Contributor

Re: Capturing Disk write data

DO you have the Performance Agent (previously called measureware) on this system? If so, this is a pretty trivial activity.

To check if you have it installed, see if you get any meaningful output from:

ovpa status

or

mwa status

HTH

Duncan

HTH

Duncan
Mohanasundaram_1
Honored Contributor

Re: Capturing Disk write data

Hi,

I pretty much zeroed-in to Glanceplus as I understood the system tools were not giving this info.

I do not have measureware or performance agent, only glanceplus is available. Hence I was trying to find if there are command line options using glance to capture such data.

Again, the captured data is to be used by another team to do some analysis, probably using Excel.

I am aware that I could use glance -j but I am not sure if that will capture the disk writes as a seperate entity.

With regards,
Mohan.
Attitude, Not aptitude, determines your altitude
Duncan Edmonstone
Honored Contributor
Solution

Re: Capturing Disk write data

Perf Agent would have been more straightforward, but you can do it with glance as well...

Create a file (I called it /tmp/disk_rw) with the following contents:

print "-------- device wKB/s"
disk loop {
print GBL_STATTIME, " ",BYDSK_DISKNAME|15,
BYDSK_PHYS_WRITE_BYTE_RATE|8|0
}

Then reference this from glance with a suitable interval:

glance -aos /tmp/disk_rw -j 10

That samples every 10 seconds.

HTH

Duncan

HTH

Duncan
Mohanasundaram_1
Honored Contributor

Re: Capturing Disk write data

Hi Duncan,

That is what I was looking for.

One small clarification in this, The interval is for every 10 seconds but is there a parameter to specify the count, that is, how many times the reading will be recorded?

I am assuming the given syntax will capture the information for each disk in the system.

With regards,
Mohan.
Attitude, Not aptitude, determines your altitude
Duncan Edmonstone
Honored Contributor

Re: Capturing Disk write data

Mohan,

Well you can read the glance man page as well as I can!

glance -aos /tmp/disk_rw -j 10 -iterations 3

Note minimum number of iterations is 2

HTH

Duncan

HTH

Duncan
Mohanasundaram_1
Honored Contributor

Re: Capturing Disk write data

Hi,

Thanks to Duncan and Hakki for their time. Duncan had provided the information I was seeking for.

While I looked at the man pages, I wanted to know from people who have really used glance to capture such information and their direct inputs.

With regards,
Mohan.
Attitude, Not aptitude, determines your altitude