Archived from groups: comp.sys.ibm.pc.hardware.storage (
More info?)
On Mon, 07 Jun 2004 11:34:16 +0200, Marc de Vries
<marcdevries@geen.spam.zonnet.nl> wrote:
>On 4 Jun 2004 04:34:44 -0700, thelaery@hotpop.com (Laery) wrote:
>
>>Hi thanks for respondig.
>>
>>Marc de Vries <marcdevries@geen.spam.zonnet.nl> wrote in message news:<a25pb0h1vf9tmleedhamc3j42raa3hnbkl@4ax.com>...
>>> On 30 May 2004 10:43:16 -0700, thelaery@hotpop.com (Laery) wrote:
>>>
>>> >Hi,
>>> >
>>> >Have a promise SX4 controller with 128MB ECC ram and 4 maxtor 80GB
>>> >drives in raid-5 on a gigabyte 7dpxdw-p with 512MB ECC and 1 athlon
>>> >2600+MP.
>>>
>>> I have the same controller also with 128MB with 4 Maxtors diamondmax
>>> 9+ 120GB drives in Raid5.
>>>
>>> >I've been testing different setting but always get low read and write
>>> >performance. (I know that writing is supposed to be slow)
>>>
>>> What kind of performance do you get and in what kind of tests? What do
>>> you call low?
>>HDTach: 44max 13 min 17 average
>
>HDTach doesn't seem to be a very reliable program to test performance.
>Xbitlabs doesn't use it anymore because it is not reliable and
>specially so for Raid arrays.
>
>On the forum I see lots of peolpe complaining about low performance
>results on raid arrays.
>
>But I'm willing to test it on my machine. In read only mode I can just
>run it on my existing array without losing data?
I just tested it yesterday on my desktop.
Well, you can forget about the HDTach results because they are bogus.
It reports around 20MB/s sequential read speed which I can prove it
not correct.
I use the Raid5 array on the promise controller as data disk. I also
have a single Hitachi 60GB 7K250 as bootdisk.
I copied a CD image file from the hitachi disk to the array and
another image file from the array back to the bootdisk. I monitored
those actions with performance monitor to check on the read bytes/s
and the write bytes /s.
When reading from the array I am writing to the bootdisk. So in that
situation I am limited by the write speed of the bootdisk. Around 20 -
23MB/s. But HDTach shouldn't have that problem, so should have a much
higher number.
When writing to the array, I am reading from the bootdisk so it
shouldn't limit me as much as in the above situation. Then I get
around 30 - 35 MB/s.
Unless someone can explain to me why reading from a Raid5 would be
slower then writing I think this proves that the values from HDTach
are incorrect.
Regards,
Marc