Re: RAIDframe performance (RAID-5)

[George Michaelson <geeohgeegeeoh%gmail.com@localhost>]

> I've done six tests, for bsize/fsize 16K/2K-->32K/4K-->64K/8K  
> respectively, and both 64K and 32K stripe sizes. Very interesting.  
> Three winners and three losers with absolutely nothing in between.  
> The 64K stripe size with 64K bsize probably hits the absolute  
> optimal performance (this is seems to be very close to 2x the raw  
> single disk performance) but 32K/32K and 32K/64K are both also very  
> good at 80+MB/s both read AND write.
>
> ** BAD: 64K stripe size, 16K block size, 2K frag size:
>
> Version  1.03       ------Sequential Output------ --Sequential  
> Input- - --Random-
>                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--  
> - --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec  
> %CP  /sec %CP
> pear           300M 12310   5 12189   4  6987   1 84635  63 91295   
> 16 521.8   2
>
>
> ** BAD: 64K stripe size, 32K block size, 4K frag size:
>
> Version  1.03       ------Sequential Output------ --Sequential  
> Input- - --Random-
>                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--  
> - --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec  
> %CP  /sec %CP
> pear            300M 11648   5 11803   4  8717   2 89978  66 92012   
> 16 516.1   2
>
>
> ** GOOD: 64K stripe size, 64K block size, 4K frag size:
>
> Version  1.03       ------Sequential Output------ --Sequential  
> Input- - --Random-
>                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--  
> - --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec  
> %CP  /sec %CP
> pear           300M 96252  46 97565  32 19439   6 91624  66 91608   
> 14 310.9   1
>
>
> ** BAD: 32K stripe size, 16K block size, 2K frag size:
>
> Version  1.03       ------Sequential Output------ --Sequential  
> Input- - --Random-
>                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--  
> - --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec  
> %CP  /sec %CP
> pear           300M  8839   4  8770   3  6628   2 78156  58 91332   
> 17 525.1   2
>
>
> ** GOOD: 32K stripe size, 32K block size, 4K frag size:
>
> Version  1.03       ------Sequential Output------ --Sequential  
> Input- - --Random-
>                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--  
> - --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec  
> %CP  /sec %CP
> pear.johani.or 300M 81546  38 90802  34 20711   7 81892  61 91937   
> 16 364.5   1
>
>
> ** GOOD: 32K stripe size, 64K block size, 8K frag size:
>
> Version  1.03       ------Sequential Output------ --Sequential  
> Input- - --Random-
>                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--  
> - --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec  
> %CP  /sec %CP
> pear           300M 84566  40 90798  33 20682   6 83047  58 92784   
> 15 270.2   1
>
>
> > Oh.. and don't worry about rebuilding parity before doing the tests
> > -- parity only matters if you care about the data in the event of  
> > afailure ;)
>
> Right, I actually knew that, but I was not thinking straight. Thanks  
> for pointing it out. And many thanks for helping me to understand  
> this much better than before.
>
> Johan

the summary is really good. can this be put somewhere useful like a  
NetBSD web or a wiki?

> ** GOOD: 64K stripe size, 64K block size, 4K frag size:
> ** GOOD: 32K stripe size, 32K block size, 4K frag size:
> ** GOOD: 32K stripe size, 64K block size, 8K frag size:

and thanks for doing the tests!

-George