Re: RAID stripe size question

Mikael,

On 7/18/06 6:34 AM, "Mikael Carneholm" <Mikael(dot)Carneholm(at)WirelessCar(dot)com>
wrote:

> However, what's more important is the seeks/s - ~530/s on a 28 disk
> array is quite lousy compared to the 1400/s on a 12 x 15Kdisk array

I'm getting 2500 seeks/second on a 36 disk SATA software RAID (ZFS, Solaris
10) on a Sun X4500:

=========== Single Stream ============

With a very recent update to the zfs module that improves I/O scheduling and
prefetching, I get the following bonnie++ 1.03a results with a 36 drive
RAID10, Solaris 10 U2 on an X4500 with 500GB Hitachi drives (zfs
checksumming is off):

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
thumperdw-i-1 32G 120453 99 467814 98 290391 58 109371 99 993344 94
1801 4
------Sequential Create------ --------Random
Create--------
-Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec
%CP
16 +++++ +++ +++++ +++ +++++ +++ 30850 99 +++++ +++ +++++
+++

=========== Two Streams ============

Bumping up the number of concurrent processes to 2, we get about 1.5x speed
reads of RAID10 with a concurrent workload (you have to add the rates
together):

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
thumperdw-i-1 32G 111441 95 212536 54 171798 51 106184 98 719472 88
1233 2
------Sequential Create------ --------Random
Create--------
-Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec
%CP
16 26085 90 +++++ +++ 5700 98 21448 97 +++++ +++ 4381
97

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
thumperdw-i-1 32G 116355 99 212509 54 171647 50 106112 98 715030 87
1274 3
------Sequential Create------ --------Random
Create--------
-Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec
%CP
16 26082 99 +++++ +++ 5588 98 21399 88 +++++ +++ 4272
97

So that¹s 2500 seeks per second, 1440MB/s sequential block read, 212MB/s per
character sequential read.
=======================

- Luke