Hi All,

I have got RAID10 disks and my system is IO bound. I thought that RAID
would take away all striping problems, but that is not necessarily the
case, why am I having IO issues despite the RAID hw? WIll ASM help

Thanks for any advice.

Vissu

<vissuyk@yahoo.com> wrote in message
news:1116557933.338509.122080@g43g2000cwa.googlegr oups.com...
> Hi All,
>
> I have got RAID10 disks and my system is IO bound. I thought that RAID
> would take away all striping problems, but that is not necessarily the
> case, why am I having IO issues despite the RAID hw? WIll ASM help
>
> Thanks for any advice.
>
> Vissu

RAID10 includes striping. It's not going to "take away all striping
problems".

Maybe you simply have bigger load than is your disk IO capacity. You
can add more disks or use quicker ones. That's the only answer that I
can give to such generic question.

--
Dusan Bolek

vissuyk@yahoo.com wrote:
> Hi All,
>
> I have got RAID10 disks and my system is IO bound. I thought that RAID
> would take away all striping problems, but that is not necessarily the
> case, why am I having IO issues despite the RAID hw? WIll ASM help
>
> Thanks for any advice.
>
> Vissu
>
It's all about spindles. More spindles = more throughput.
More spindles + more controllers = even better throughput.


What RAID10 (not RAID01?) - what controller(s), how many disks?

--
Regards,
Frank van Bortel

vissuyk@yahoo.com wrote:
> Hi All,
>
> I have got RAID10 disks and my system is IO bound. I thought that RAID
> would take away all striping problems, but that is not necessarily the
> case, why am I having IO issues despite the RAID hw? WIll ASM help
>
> Thanks for any advice.
>
> Vissu
>
It's all about spindles. More spindles = more throughput.
More spindles + more controllers = even better throughput.


What RAID10 (not RAID01?) - what controller(s), how many disks?

--
Regards,
Frank van Bortel

vissuyk@yahoo.com wrote:
> Hi All,
>
> I have got RAID10 disks and my system is IO bound. I thought that RAID
> would take away all striping problems, but that is not necessarily the
> case, why am I having IO issues despite the RAID hw? WIll ASM help
>
> Thanks for any advice.
>
> Vissu
>

Without knowing your actual RAID configuration it's hard to determine
the problem. Here are some questions to consider though.

How many disks in the stripe set? The more disks, the less chance of
head contention.

Have you reached the capacity of your controller?

Is this a SAN configuration? If so, what other applications (possibly on
other unrelated servers) are sharing the physical disks. Do *NOT*
believe what SAN vendors say about their caches eliminating contention.
I have personally seen situations where physical disk contention with
another has caused a database's average i/o time to go from milliseconds
to more than 2 seconds!

--
To reply by email remove "_nospam"

vissuyk@yahoo.com wrote:
> Hi All,
>
> I have got RAID10 disks and my system is IO bound. I thought that RAID
> would take away all striping problems, but that is not necessarily the
> case, why am I having IO issues despite the RAID hw? WIll ASM help
>
> Thanks for any advice.
>
> Vissu
>

Without knowing your actual RAID configuration it's hard to determine
the problem. Here are some questions to consider though.

How many disks in the stripe set? The more disks, the less chance of
head contention.

Have you reached the capacity of your controller?

Is this a SAN configuration? If so, what other applications (possibly on
other unrelated servers) are sharing the physical disks. Do *NOT*
believe what SAN vendors say about their caches eliminating contention.
I have personally seen situations where physical disk contention with
another has caused a database's average i/o time to go from milliseconds
to more than 2 seconds!

--
To reply by email remove "_nospam"

Define 'IO bound'? Can you trace it to controller, channel or disk? What
is exact config and OS? What tools are you using to determine problem?
Do you have a RAID venfdor or are you doing this on the fly?

RAID 1+0 includes stripping. Did you mean take away stripping with parity
(aka RAID 5 and the likes) problems?

What exactly do you mean by IO issues? Are you suffering flow slow reads or
writes? What is the percentage of read operations vs write? Do you have
physically separate spindles for the database and logs?

As you can see, there are still quite a few things to deal with besides
picking a "better" RAID configuration. If you can provide more details, we
may be able to offer some thoughts on how to identify and address the issues
you're facing.


joe.


<vissuyk@yahoo.com> wrote in message
news:1116557933.338509.122080@g43g2000cwa.googlegr oups.com...
> Hi All,
>
> I have got RAID10 disks and my system is IO bound. I thought that RAID
> would take away all striping problems, but that is not necessarily the
> case, why am I having IO issues despite the RAID hw? WIll ASM help
>
> Thanks for any advice.
>
> Vissu
>

Define 'IO bound'? Can you trace it to controller, channel or disk? What
is exact config and OS? What tools are you using to determine problem?
Do you have a RAID venfdor or are you doing this on the fly?