topic Re: Buffer Cache Hit Ratio in Operating System - HP-UX

Buffer Cache Hit Ratio

Steve Huizenga — Wed, 29 Aug 2001 17:00:37 GMT

Does anyone know how I can see my buffer cache hit ratio?

Re: Buffer Cache Hit Ratio

Sridhar Bhaskarla — Wed, 29 Aug 2001 17:03:33 GMT

Sar -b gives you buffer hit ratio.

#sar -b 2 10

Give %rcache and %wcache averaged every 2 secs
for 10 iterations.

-Sri

Re: Buffer Cache Hit Ratio

Magdi KAMAL — Thu, 30 Aug 2001 06:21:39 GMT

Hi Steve,

I agree with Sridhar,
#sar -b IntervalInSeconds NumberOfTimes

%rcache : Give you the read cache percentage.
%wcache : Give you the write cache percentage.
bread/s : Number of physical reads per second.
bwrit/s : Number of physical writes per second.
lread/s : Number of logical reads ( from buffer ) per second.
lwrit/s : Number of logical writes( to buffer ) per second.
pread/s : Number of reads per second from character device using the physio() ( Raw i/o ) mechanism.
pwrit/s : Number of writes per second to character device using the physio() ( Raw i/o ) mechanism.

Magdi

Re: Buffer Cache Hit Ratio

Rick Bowles — Thu, 30 Aug 2001 19:21:36 GMT

You can also see it in glance with "d" disk report, and "f" forward to page two of the disk report.

Re: Buffer Cache Hit Ratio

Wodisch — Thu, 30 Aug 2001 20:00:47 GMT

Hello,

to see the buffer hit rate as it was, say, yesterday,
you have to activate the "System Activity Data collector",
see the man page for "sadc" for this. It does contain the
"crontab" entries you need for this.
Thereafter you can call "sar -b" and see today's
statistics, or you may use the "start" and "end" options
to tell "sar" the timeframe you are interested in.

HTH,
Wodisch