Performance of 1850 with scsi and software raid 1?

David Hubbard dhubbard at
Tue Mar 1 08:43:01 CST 2005

jason andrade wrote:
> On Tue, 1 Mar 2005, David Hubbard wrote:
>> Come on, someone must have an 1850 non-raid that has
>> done some disk benchmarks on linux? :-)  I need to
>> know this data so I can make a purchase decision.
> ask dell to loan you one for eval purposes and then post
> your results back to the list so you can answer your question ? :-)

Okay, I did get someone to help with some Bonnie results.
First, the results of me running Bonnie on an SC1425
with dual 80 GB SATA drives, software mirrored under
RHEL 3.0 U4 running on ext3:

      ------Sequential Output------ --Sequential Input- --Random-
      -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
 Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
   4G 37546  96 55557  32 23180  10 30657  67 54005  12 321.8   1

Here are the results of Bonnie running on CentOS 3, ext3
file system on an 1850 with 10krpm SCSI drives.

      ------Sequential Output------ --Sequential Input- --Random-
      -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
   MB K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
 1997 47323  56 44906  31 20997   9 28152  18 28534   6 384.0   1

Neither server has been optimized from the OS defaults in
any way.  So it looks like write performance is actually
up to 10 MB/sec lower on the 1850 with SCSI compared to
SC1425 with SATA.  Block read performance is nearly half
what it is on the SC1425.  So it appears Dell's choice of
SCSI controllers are still lacking on the PowerEdge series
and a raid controller is necessary to get any useful
performance out of the SCSI-based systems.  This is the
same problem I've had with the 1750 and 2650, but those
are even worse with read/write rates in the teens.  On
the other hand, systems with the same 10krpm drives
and a run of the mill Adaptec controller often show full
disk speed when tested under the same OS configuration,
so we're talking 50 to 60 MB/sec and higher I/O with less
cpu, like SCSI should provide.


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