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Old 02-07-2012, 07:53 PM
Ken Smith
 
Default Centos 5.6 3ware raid 5

Hi, I've seen comments about the poor performance of these cards with
raid 5 configs. I have an old card with 3 x 500G IDE drives connected in
raid 5 and I'm getting around 10mb/s write performance. :-(

I'm seeing high iowait figures at times and associated very high cpu
load average figures, probably because, under load, everything is
stacked up waiting for the disks to actually do something.

A non-raid sata disk in the same machine manages 70mb/s

Does anyone know what the performance is like if I used the 3ware just
as an IDE controller? I could then switch to software raid5?

Thanks

Ken

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Old 02-08-2012, 01:27 PM
Ross Walker
 
Default Centos 5.6 3ware raid 5

On Feb 7, 2012, at 3:53 PM, Ken Smith <kens@kensnet.org> wrote:

> Hi, I've seen comments about the poor performance of these cards with
> raid 5 configs. I have an old card with 3 x 500G IDE drives connected in
> raid 5 and I'm getting around 10mb/s write performance. :-(
>
> I'm seeing high iowait figures at times and associated very high cpu
> load average figures, probably because, under load, everything is
> stacked up waiting for the disks to actually do something.
>
> A non-raid sata disk in the same machine manages 70mb/s
>
> Does anyone know what the performance is like if I used the 3ware just
> as an IDE controller? I could then switch to software raid5?

I'm sure you can, but if that's what you want why not just get a better SATA card or a better RAID card?

-Ross

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Old 02-08-2012, 05:59 PM
"Timo Neuvonen"
 
Default Centos 5.6 3ware raid 5

> Hi, I've seen comments about the poor performance of these cards with
> raid 5 configs. I have an old card with 3 x 500G IDE drives connected in
> raid 5 and I'm getting around 10mb/s write performance. :-(
>
> I'm seeing high iowait figures at times and associated very high cpu
> load average figures, probably because, under load, everything is
> stacked up waiting for the disks to actually do something.
>
> A non-raid sata disk in the same machine manages 70mb/s
>
> Does anyone know what the performance is like if I used the 3ware just
> as an IDE controller? I could then switch to software raid5?

Since you have IDE drives, you obviously have 3ware 7506 card, which is very
old. I'm not sure when it was released but that might have been before Y2k.
Anyway, at least 10 years ago. It's not fair to talk about "3ware card
performance" without specifying the card when you mean that old card. Their
9650/9750/9690 of today are more than one generation newer, there has been
8xxx and 9000/9500 series that also are obsolete now.

If yoy use 3 drives and configure 7506 as a transparent controller for each
of them, and set up a software raid, then all the drives are behind a single
pci slot, which also could be a bottleneck if you don't have a 64-bit pci
slot.

That said, I seriously recommend jumping to something more up-to-date
technology. But don't expect that newer 3ware cards were even close to that
slow.

--
TiN


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