Re: RAID 5 throughputs

On Sat, 19 Aug 2006, [email protected] wrote:

> Yeah, infact it is in a PCI-X slot @66Mhz.
>
> On 8/19/06, Justin Piszcz <[email protected]> wrote:
>> 
>> 
>> On Sat, 19 Aug 2006, [email protected] wrote:
>> 
>> > Hi All,
>> >
>> > I have a storage system with 12 Maxtor 7200 rpm 250GB hard drives in
>> > RAID 5 configuration with one hot spare. Maxtor claims that each drive
>> > is capable of providing 56 MB/s sustained throughput. My host system
>> > is connected to it using 64bit ultra320 Adaptec SCSI card. The host
>> > system has 3.0 GHz pentium 4 (with HT) processor and 4 GB of RAM
>> > running linux kernel 2.6.9. I was wondering what order of "maximum"
>> > sequential read/write, random read/write throughput should i expect
>> > using them. I am using some of the benchmarking tools like Bonnie,
>> > Bonnie++, tiobench, dd, iometer etc. However the results from them
>> > have been very depressing. Theoretically i should be able to achieve a
>> > read sequential throughput close to min(10*56 = 560, 320) = 320 MB/s.
>> > However my results are no way close to it. I was wondering if anybody
>> > can give me some insight of what order of practical throughputs i
>> > should expect using linux and what other factors may be creating
>> > bottlenecks.
>> >
>> > TIA
>> > -
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>> >
>> 
>> Is your 64bit ultra320 card in a 64bit PCI + 66MHZ slot?
>> 
>> If not, you will be limited to 133mb/s.
>> 
>> 
>

What speeds are you currently seeing, r/w?

Have you tried making a 3-drive raid5 and increasing it by 1 drive at a 
time to see if there is any difference in speed?

Justin.