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From: Luke Lonergan <llonergan@greenplum.com>
To: Mikael Carneholm <Mikael.Carneholm@WirelessCar.com>
To: Ron Peacetree <rjpeace@earthlink.net>
To: pgsql-performance@postgresql.org
Subject: Re: RAID stripe size question
Date: Tue, 18 Jul 2006 11:56:45 -0700
Message-ID: <C0E27CFD.2A4AC%llonergan@greenplum.com> (raw)
In-Reply-To: <7F10D26ECFA1FB458B89C5B4B0D72C2B4E4C31@sesrv12.wirelesscar.com>

Mikael,

On 7/18/06 6:34 AM, "Mikael Carneholm" <Mikael.Carneholm@WirelessCar.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

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Message-ID: <C0E27CFD.2A4AC%llonergan@greenplum.com>
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  To: pgsql-performance@postgresql.org
  Cc: llonergan@greenplum.com, Mikael.Carneholm@WirelessCar.com, rjpeace@earthlink.net
  Subject: Re: RAID stripe size question
  In-Reply-To: <C0E27CFD.2A4AC%llonergan@greenplum.com>

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