Re: RAID 5 performance issue.

[Andrew Clayton <andrew@pccl.info>]

On Fri, 5 Oct 2007 13:53:12 +0100, Andrew Clayton wrote:


> Unfortunately problem remains.
> 
> I'll try the noop scheduler as I don't think I ever tried that one.

Didn't help either, oh well.

If I hit the disk in workstation with a big dd then in iostat I see it
maxing out at about 40MB/sec with > 1 second await. The server seems to
hit this with a much lower rate, < 10MB/sec maybe

I think I'm going to also move the raid disks back onto the onboard
controller (as Goswin von Brederlow said it should have more bandwidth
anyway) as the PCI card doesn't seem to have helped and I'm seeing soft
SATA resets coming from it.

e.g

ata6.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2
ata6.00: irq_stat 0x00020002, device error via D2H FIS
ata6.00: cmd 35/00:00:07:4a:d9/00:04:02:00:00/e0 tag 0 cdb 0x0 data 524288 out
         res 51/84:00:06:4e:d9/00:00:02:00:00/e2 Emask 0x10 (ATA bus error)
ata6: soft resetting port
ata6: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
ata6.00: configured for UDMA/100
ata6: EH complete


Just to confirm, I was seeing the problem with the on board controller
and thought moving the disks to the PCI card might help (at £35 it was
worth a shot!)

Cheers,

Andrew
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