What is the write performance if you do RAID0 instead of RAID1? I don't
have that hardware and I can't verify anything though. Also, you can use
'direct' I/O flag with "dd" command.

Thanks, Malahal.

Gon?alo Borges [borges.gonc...@gmail.com] wrote:
> 
> Hi All...
> 
> Sorry, the following could be a little bit off topic...
> 
> Does any one has an idea of what is the expected performance for a IBM
> DS 3300 system connected via open iSCSI? Using a RAID 1 with 2 disks,
> I got the following numbers:
> 
> Sequential Write:
> 
>  [r...@core12 ~]# dd if=/dev/zero of=/apoio04/b1 bs=64k count=125000
> 125000+0 records in
> 125000+0 records out
> 8192000000 bytes (8.2 GB) copied, 454.522 seconds, 18.0 MB/s
> 
> Sequential Read:
> [r...@core12 ~]# dd if=/apoio04/b1 of=/dev/null bs=64k count=125000
> 125000+0 records in
> 125000+0 records out
> 8192000000 bytes (8.2 GB) copied, 94.9401 seconds, 86.3 MB/s
> 
> I restricted the RAM to be only 1GB, therefore there are no cache
> effects in these numbers. Because the read stats are good, we exclude
> network bottlenecks. Nevertheless, we were expecting more or less the
> performance of a single disk (~50MB/s) for the write tests and we are
> getting less than half. I do not know if this is really the physical
> limit of the system or if there is a problem somewhere...
> 
> I could not find any IBM official numbers, therefore, I though that
> someone over here could give me any hint about the numbers they are
> getting...
> 
> Thanks in Advance
> Cheers
> Goncalo Borges
> > 

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