Justin Tripp wrote:
>
<...>
>
> 3ware, on the other hand, is a hardware raid. As far as your computer is
> concerned you have a SCSI controller hooked to a pci slot. The overhead
> of IDE disks is not seen by the processor since it only interacts with the
> Raid controller and cannot see the individual disks. I have a 3ware
> controller with 4 40G disks running RAID 5 with XFS as the underlying
> filesystem. It works quite well.
We are testing the 7+1 raid5 solution on a Rocky 3782-EV motherboard
(i815E)
and a p3-800eb with 2x256MB ram. And the performace with the raid5
hardware
was "bad":
* ~6GB nfsv3 transfert write to an ext2 partition takes ~20 min
against 1h40 on the raid5 hardware array
* mkfs.ext2 of 250MB takes 1h30...
* mkfs.xfs was in the order of 10 sec. but the write was even longer
(I stopped after 2h!)
3ware support believe that is is cause by the memory subsystem
which is too slow...
<quote>
'hdparm -T /dev/sda' : This is the buffer cache read speed. This is
the upper-bound for the system. If this
number
is not over 100MB/s, the system you are on
has
a memory load-copy bottleneck with Linux.
</quote>
It could be since hdparm on the raid5 server gives:
Timing buffer-cache reads: 128 MB in 1.28 seconds =100.00 MB/sec
against on a 440BX motherboard is:
Timing buffer-cache reads: 128 MB in 0.72 seconds =177.78 MB/sec
Bonnie++ Version 1.00g
a) ext2 partition on the boot disk - linux 2.4.5ac13
alineas,1G,10779,98,37033,34, 8364,
8,8237,77,25792,12,172.4,0,16,458,99,+++++,+++,25308,97,463,99,+++++,+++,2692,99
b)ext2 whole array==sda1 3ware RAID5 - linux 2.4.5ac13
alineas,1G, 2138,19, 1885, 1, 1479,
1,5473,51,57514,23,461.9,1,16,529,99,+++++,+++,25462,96,516,95,+++++,+++,3188,97
c) ext2 md0 software raid5 - linux 2.4.5ac13
alineas,1G,
8919,82,19996,19,13627,16,8809,94,47391,81,338.7,3,16,462,99,+++++,+++,24882,97,464,99,+++++,+++,2858,99
Anyone care to comment?
Regards,
Tru
--
Dr Tru Huynh | Bioinformatique Structurale
mailto:tru@xxxxxxxxxx | tel/fax +33 1 45 68 87 37/19
Institut Pasteur, 25-28 rue du Docteur Roux, 75724 Paris CEDEX 15 France
|