Hi Walter,
It looks like you're having a bottleneck on your
controller during a hot backup. This is a result of
(1) reading the data then (2) writing the data and
compressing the data within the same controller.
To answer your questions:
1. During RAID 5, all your disks are being written to
and parity rotates on each disks. You can do a search
on RAID levels on the web. One thing to note is that a
RAID 5 needs at least 4 physical drives to work
efficiently.
2. Since you are running a single A1000 with 8 slots,
I would avoid the RAID 0+1 idea. Keep the RAID 5 setup
unless you go with 10 drives, then go for RAID 1+0.
Alocate a couple of drives for redo logs (on seperate
internal disk bus within the A1000) and multiplex the
redo logs on the two drives. Keep a drive for the
archived redo logs, you can even use a bigger hard
drive that has the same form factor as the 9GB hard
drive. Try to squeeze a Hot Spare in as well. seperate
the RAID 5 drives between the two internal disk bus of
the A1000 as well. Look into backing up your database
to a TAPE device instead of hard drives. With a 8GB
database, you can restore your database in 10 minutes
with a DLT 8000, just make sure the backup software
binaries and database resides on a sperate system on
your network.
Your best bet, if you can afford it, is to return the
A1000 and get a A3500, which comes with 2 D1000's. Buy
the additional controller for redundancy and do a RAID
50 or 10. This is the best bet because of the
redundancy on the conntroller, disks and internal bus
of the system. Also implement the TAPE backup system.
I believe the A1000 is a 10 slot (for 9GB drives and
some 18GB drives). If it is only a 8 slot storage,
make adjustments accordingly, keeping the internal
disk bus in mind. Lay out your disk:
Slot 1 - RAID 5 DRIVE
Slot 2 - RAID 5 DRIVE
Slot 3 - Archived redo logs
Slot 4 - Redo Logs (Members A)
Slot 5 - EMPTY
Slot 6 - RAID 5 DRIVE
Slot 7 - RAID 5 DRIVE
Slot 8 - Redo Logs (Members B)
Slot 9 - HOT SPARE
Slot 10- EMPTY
If it is a 10 slot and you decide to go with 10 hard
drives, implement RAID 1+0 to increase write
performance. Use the Hot SPARE disk as an extra disk
to throw junk into.
Hope this helps. Let me know if I confused you more or
if you need additional info.
Regards,
Satar
--- Walter K <[EMAIL PROTECTED]> wrote:
> Hi,
>
> I'm encuntering a relatively high iowait percentage
> when my hot backups are running. The platform is Sun
> (E420 2cpu running SunOS 5.7) with an A1000 disk
> array
> (8 9Gb drives, hardware Raid-5). The array is one
> volume and all DB components (redo, archive, data,
> index, system, etc.) are on the same volume except
> for
> the binaries. The database is not large, only ~8Gb
> in
> size and the transactional volume is not much
> either.
> However, when the backups run, the iowait according
> to
> 'top' hovers between 50-70% which causes our
> application to time-out via Web Logic 6.0.
>
> The developers can't explain why the timeouts are
> occurring (WLS 6.0 is a new upgrade from 5.1). The
> SysAdmin isn't much help either.
>
> I have an opportunity to rebuild the database on
> another machine and use RAID 1+0 -- the thought
> being
> that we are choking ourselves with Raid-5 when the
> hot
> backups are performing the cp's (copies) and then
> the
> files are compressed.
>
> My first question is, how is the data distributed
> across the drives in my Raid-5 configuration? Is
> each
> disk being filled contiguously in series or is the
> data being spread around in a pseudo-striping
> manner?
>
> My second question/dilema is, the new array (another
> A1000) will have 6 18Gb drives and with Raid 1+0
> that
> shrinks to 3 drives of usable space for everything
> except redo and archive. 4 9Gb drives will be added
> in
> two mirrored sets, one for redo and the other for
> archive. I'm afraid that I will see worse I/O
> performance with the new array because it has so
> fewer
> physical drives, thus eliminating the benefit of not
> having to write the parity info.
>
> Do you concur? Knowing the two arrays I have to work
> with, which would be the better configuration?
>
> Any suggestions, recommendations would VERY much be
> appreciated.
>
> Thanks again for the feedback.
> -w
>
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