I second Marks comment on NOT recommending the 3ware cards to anyone.
I have a dual XEON 3.2 Ghz system 12 G of ram with a 3ware 8506-8 in it (8 250 G drives). The hard raid performance
was very bad. with the load avg going over 40. I then switched over to JBOD and software raid. The IO wait times
are really high and the performance sucks. Very hard to explain to my boss where the $20k went. The system is a
database server (postgres). I tried both kernel 2.4 and 2.6 with the same problem. I am now in the process of
testing the adaptec raid controller.
Jim
---------- Original Message -----------
From: Mark Watts <mrwatts@xxxxxxxxxxxx>
To: Marc Bevand <bevand_m@xxxxxxxx>
Cc: linux-raid@xxxxxxxxxxxxxxx
Sent: Fri, 30 Jul 2004 17:17:36 +0100
Subject: Re: 1x 3ware controllers vs. 2x 3ware controllers
> > Mark Watts wrote:
> > > With the performance issues I'm seeing with the 8506-4LP's I have, I
> > > wouldn't recommend them to anyone currently...
> > >
> > > The thread on LKML from a few days ago about mke2fs -j and 8506-4LP says
> > > it all, but basically and reasonable amount of I/O brings a Dual Opteron
> > > system to its knees.
> > > And by reasonable I mean copying ISO images from a usb2 drive to a raid 5
> > > (4 x 250GB maxtor) or even just formatting a 600MB partition.
> >
> > I would be interested to see the output of 'vmstat 1' while your system is
> > so slow.
> >
> > IMHO you shouldn't draw such conclusion ("reasonable amount of I/O brings a
> > Dual Opteron system to its knees") from your particular case. The 3 HT
> > links of the Opteron make this CPU particularly adapted to I/O operations.
>
> Well its the only conclusion I *can* come to at this time.
> When you move from a UP 1.8Ghz P4 with single EIDE disks to SMP Opteron with 4
> times the ram and a hardware raid card, you tend to assume that performance
> in all areas will go up.
> When it doesn't, and you find yourself watching screen redraws while you
> format a 600GB partition (ext3) you do feel the need to blame something :)
>
> I'm all ears for suggestions on what me be wrong or things I can try to
> improve performance.
>
> >
> > Personnaly, on a dual Opteron, I am able to read datas from 4 SATA disks at
> > about 225 MB/s, with CPU time used at about 32%, awd with a system still
> > reasonably responsive.
>
> I'm seeing ~80MB/sec reading from the 3ware raid-5 according to hdparm and
> bonnie++
> Write performance is around 25MB/sec according to bonnie++.
>
> Mark.
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