Re: Performance with 2 AMD/Opteron 2.6Ghz and 8gig

Mikael,

> -----Original Message-----
> From: Mikael Carneholm [mailto:Mikael(dot)Carneholm(at)WirelessCar(dot)com]
> Sent: Friday, July 28, 2006 2:05 AM
>
> My bonnie++ results are found in this message:
> http://archives.postgresql.org/pgsql-performance/2006-07/msg00164.php
>

Apologies if I've already said this, but those bonnie++ results are very
disappointing. The sequential transfer rates between 20MB/s and 57MB/s
are slower than a single SATA disk, and your SCSI disks might even do
80MB/s sequential transfer rate each.

Random access is also very poor, though perhaps equal to 5 disk drives
at 500/second.

By comparison, we routinely get 950MB/s sequential transfer rate using
16 SATA disks and 3Ware 9550SX SATA RAID adapters on Linux.

On Solaris ZFS on an X4500, we recently got this bonnie++ result on 36
SATA disk drives in RAID10 (single thread first):

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 +++++ +++
+++++ +++

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 that's 2500 seeks per second, 1440MB/s sequential block read, 212MB/s
per character sequential read.

- Luke