topic Re: Question on VA in Disk Enclosures

Question on VA

Mike_305 — Mon, 12 Aug 2002 15:16:31 GMT

Hi,

We have purchase the new L2000 with VA7100 and would like to know couple things. What is the throughput of the new box's I/O subsystem? I don't mean how fast is the fibre channel, rpms of the disks, etc. What I really would like is something like a megs/sec of random read/write consistent megs/sec of random read/write burst. I say random because that???s mostly how our application system works (as opposed to sequential).

If anyone has any links or docs, I will appreciate that or even answer to my questions.

Thanks,

Mike

Re: Question on VA

Christopher McCray_1 — Mon, 12 Aug 2002 15:23:50 GMT

Hello,

Is this what you are looking for?

http://www.hp.com/products1/storage/products/disk_arrays/midrange/va7100/infolibrary/7100_product_brief.pdf

http://www.hp.com/products1/storage/products/disk_arrays/infolibrary/va_perf_analysis.pdf

Hope this helps

Chris

Re: Question on VA

Scott_14 — Mon, 12 Aug 2002 17:57:58 GMT

Hi Mike:

I dont know if this is what your after, but this link is nice for getting some information.
http://www.spec.org/

on the left side you can select search, then
you can chose like system, and hp, and it will give you a listing and you can select which model you want to see benchmarks for.

scott

Re: Question on VA

Leif Halvarsson_2 — Mon, 12 Aug 2002 18:48:50 GMT

Hi
When I looked at the VA7100 and VA7400 some month ago I could find performance specifications in the documentation but now I can't longer find it. If I remember correct it was something like

VA7100: 3500 IOPS disk, 15000 IOPS chache, 90MB/s transfer rate.
VA7400: About double compared to VA7100.
Have a look at:
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x7239eea29889d611abdb0090277a778c,00.html

There you can find a file system benchmark and some test results.

Re: Question on VA

Tim D Fulford — Mon, 12 Aug 2002 20:17:28 GMT

OK

I'm going to answer this in a weird way, hang on...

We had fc60 two controllers, 12 LUNS, 256MB cache per controller. We used this for a OLTP DB(Random) and we
I used to plot graphs, and I would get a pritty straight line of disk % Vs IO/s. The gradient of the line gives the average service time, 4-5ms. Pritty good, each IO was about 2-4kB so...max throughput
12LUNx3kB(1/0.0045) ==> 8,000kB/s or 8MB/s (could see more)

We have now replaced the fc60 with VA7400, two controllers 512MB per controller. I see same behaviour except service times are 1-2ms. Thus...
12LUNx3kBx(1/0.0015) ==> 24,000kB/s

The VA7100 is a "lesser" disk-subsystem. but I think it has similar CPU's AND it can hold LOTS of disks than an fc60. You can increase the random throughput simply by striping over more LUNS. Also remember that bigger disks can give performance gains as well as faster disks as the head does not have to travel so far between tracks.

You really need to test it against your database/Application to get a good figure, but If you already know what the demands are now; on your current system; you have a head start. I'd start by plotting disk% Vs IO/s & see what that looks like (MeasureWare)

Regards

Tim

Re: Question on VA

Mike_305 — Mon, 12 Aug 2002 21:23:39 GMT

Hi Tim,

I know at the bottom of your e-mail you told Measure Ware to use, do you have any other recommendation for monitoring performance or monitoring IO.

Thanks,

Mike

Re: Question on VA

Tim D Fulford — Tue, 13 Aug 2002 17:29:27 GMT

The classic system activity reporter.....

"sar -d "

time > 60 (seconds)
n - number of times you should repeat sample.

so sar -d 15 2
It will do two samples of 15 seconds. In this the last two columns are interesting as it gives Average Service time (or slope of disk % Vs IO/s). This is the average time for an IO to be processed, also how long it took for the IO to hit the disk subsystem.

The problem with sar is that
o It is not as accurate as MW
o Is that it is not historical - However, you can set it up using cron & sa

I'm a BIG fan of MeasureWare and have solved / helped solve many a problem with it

Regards

Tim