PowerEdge 2650 and Perc3/DI

Dear aacraid-users,


we are experiencing disappointing RAID5 performance of
our brand new PowerEdge 2650 server.

The hardware configuration is as following
- PowerEdge 2650, BIOS A17
- 2 x Xeon 2.8 GHz CPUs
- 1024 MB RAM
- Perc3/DI with 128 MB cache and Firmware 2.7-1 (3170)
- 4 x harddisk drives Atlas 10K, 73 GB:
  3 of them are configured as a one RAID5 volume, 
  the remaining drive is defined as failover drive

We are running RHEL3 using a static SMP kernel and the newest
aacraid driver:

# uname -a
Linux web2 2.4.21-4.0.1.EL-smp-static-aacraid #5 SMP Mon Dec 22 11:10:12
CET 2003 i686 i686 i386 GNU/Linux

# cat /proc/scsi/aacraid/0
Adaptec Raid Controller 1.1-4[2308]
Vendor: DELL     Model: PERCRAID
kernel: 2.7-1[3170]
monitor: 2.7-1[3170]
bios: 2.7-1[3170]
serial: fef010d3

The new driver package (aacraid-drv_1.1.4-rhel3.rpm)
was posted from Adaptec on 16-Dec-2003 
(source:
http://www.adaptec.com/worldwide/support/driverdetail.html?sess=no&language=English+US&cat=%2fOperating+System%2fRed+Hat+Linux&filekey=aacraid-drv_1.1.4-rhel3.rpm)


We performed tests using iozone:

(1) running IOZONE with 2 GB file on PowerEdge 2650
describe above: result is read/write data rates of about 32 MBytes/s

# /opt/iozone/bin/iozone  -i0 -i1 -s 2048M
        Iozone: Performance Test of File I/O
                Version $Revision: 3.217 $

        File size set to 2097152 KB
        Command line used: /opt/iozone/bin/iozone -i0 -i1 -s 2048M
        Output is in Kbytes/sec
        Time Resolution = 0.000001 seconds.
        Processor cache size set to 1024 Kbytes.
        Processor cache line size set to 32 bytes.
        File stride size set to 17 * record size.
                                                            
              KB  reclen   write rewrite    read    reread    
         2097152       4   31317   33023    32036    30945



(1) running IOZONE with 2 GB file on Celeron 1GHz
    

On an much more older system (Celeron 1GHz running RedHat Linux 8.0,
512 MB RAM, 3 x IDE WD800AB drives (7.2KRPM) bound together with
software RAID level 5), the iozone test shows that compared to
the PE2650 writing is slower but reading ist much more faster.

# /opt/iozone/bin/iozone  -i0 -i1 -s 2048M
        Iozone: Performance Test of File I/O
                Version $Revision: 3.217 $, Compiled for 32 bit mode

        File size set to 2097152 KB
        Command line used: /opt/iozone/bin/iozone -i0 -i1 -s 2048M
        Output is in Kbytes/sec
        Time Resolution = 0.000001 seconds.
        Processor cache size set to 1024 Kbytes.
        Processor cache line size set to 32 bytes.
        File stride size set to 17 * record size.

              KB  reclen   write rewrite    read    reread    
         2097152       4   22192   22985    45763    44727



Questions:

Is disabling the ROMB (raid on mother board) and running
software RAID a better solution concerning performance
and stability?

Is configuring the 4 harddisks as one RAID1 volume
a solution to get much more performance? If yes: 
would it ever be faster than software RAID?


Are there any other options?


Thank you very much in advance & cheers,
Peter


PS: There was no other load on the machines during the
tests.

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