topic 256k for stripe size in Operating System - HP-UX

256k for stripe size

Miguel Angel Aliaga — Wed, 28 Nov 2001 20:13:16 GMT

Helo,

I??m looking for a way to create a LVM lvol using stripping with stripe size = 256k.
When I see the man pages for lvcreate command, I see the max size for stripe is 32k.

Any suggestion ?

I`m am working with 2 XP256, and we are wondering if using stripping or using distributed policy of LVM.

Any experience about this ?

Thanks

Re: 256k for stripe size

Craig Rants — Wed, 28 Nov 2001 20:19:13 GMT

Miguel,
To strip most effeciently, find out the block size of you XP.

For instance on my autoraids it uses 64 so I strip at 64, so there is not waste.

lvcreate -l ???SIZE??? -i 2 -I 64 -s y (???n lvol#) /dev/vg0#

Good Luck,
C

Re: 256k for stripe size

A. Clay Stephenson — Wed, 28 Nov 2001 20:20:37 GMT

Hi Miguel:

That parameter is specified in kilobytes so simply use -I 256. I seldom see any benefits above 64 since the whole idea is tyo spread the I/O over multiple paths.

Clay

Re: 256k for stripe size

Sanjay_6 — Wed, 28 Nov 2001 20:20:49 GMT

Hi Miguel,

The stripe size can be 4-32768 KB .

Do a "man lvcreate" and see that the stipe size is specified in KB and can be 4 to 32768.

Hope this helps.

Regds

Re: 256k for stripe size

harry d brown jr — Wed, 28 Nov 2001 20:23:58 GMT

Miguel,

You can also do "extent based striping":

http://forums.itrc.hp.com/cm/QuestionAnswer/1,11866,0xf904c7af36b7d5118ff10090279cd0f9,00.html

live free or die
harry

Re: 256k for stripe size

Miguel Angel Aliaga — Wed, 28 Nov 2001 22:08:52 GMT

Thanks, when I excuted the man lvcreate I mistaked and I thought the limit was 32kb, but sorry, it`s expressed in kilobytes, !!!!!!

Thanks all of you.

I have experience on EMC disks but, now we are working whith HP XP256, so I would like to hear about experiences over this platform.
I always used stipping over EMC, it works fine, but over XP we are doing tests and any experience will be gratefull.

Re: 256k for stripe size

Sridhar Bhaskarla — Wed, 28 Nov 2001 23:02:07 GMT

Miquel,

We do have XP256/512s and I tried to do some benchmarking with different stripe sizes. However, these benchmarks need not be true and the performance is entirely dependent on your application and the way it reads/writes. So, I would say to benchmark your application against different stripe sizes than looking for a generic recommendation.

If you get some chance and if the data is not too much, you may want to stripe the file systems with different stripe sizes and loadtest.

One thumb rule in performance management is "it depends".

-Sri