Re: Raid Configurations and Oracle

In article <DyB1w2.K8_at_avenger.daytonoh.ncr.com>, David Jordan <David.T.Jordan_at_DallasTX.ncr.com> writes:
|>
|> ==========mthomas_at_digital.net, 9/23/96==========
 <snip>
|>
|> Mary,
|>
|> My experience comes from using an NCR 3550 system configured as Raid 5. Under
|> this configuration, daily hot backups took 10+ hours to complete a 14GB
|> database. As you can appreciate, this was intolerable. We reconfigured the
|> system by going to Raid level 1 only, and the hot backup time dropped to 5
|> hours and the users noticed a decrease in the length of queries.
|>
|> By going to Raid level 1, we cut our available Raid storage down by half, but
|> it was worth it. There seems to be considerable controller overhead in
|> running Raid 5. Consider this as you plan.
|>
|> In all fairness, though, please realize our backup methodology is not cutting
|> edge. We are using the Unix dd command. Soon we will suppliment our backup
|> strategy with new Digital Linear Tape Drives. Estimated backup times for a
|> 20GB database is 3.17 hours.
|>
|> Best of wisdom,
|> David Jordan
|>

A few comments on the above - you state you are doing a hot back up, but then say you are using the Unix dd command - don't quite understand how that could be.

In any case - we are running a 20 GB database (two MTI/NPI-9100 RAID-5 arrays with 10.2GB of usable space each, utilizing Seagate 2.1GB 7200RPM Baracuda drives.)

The SCSI connection to the controllers is Fast Wide Single-ended and the disks themselves are standard SCSI bus.

Our system's database transactions are mostly reads, but we experience quite a few writes per day as well.

In our experience, our RAID 5 structure was FASTER than straight disks. (probably due to the Wide interface and faster disks.)

I have seen benchmarks of the MTI RAID controllers against other RAID controllers and they seem to be faster than others on the market.

As for your DLT comment - I definately agree with you, we have a DLT-4000 tape drive and can back up 23 GB worth of diskspace in around 4 hours using 'dump' (an hour faster than our 4mm autoloader)

• Al -- Al Dorrington awdorrin_at_ictest.delcoelect.com Database Admin Delco Electronics - IC CIM Unix Sysadmin Kokomo, Indiana, USA Phone: 317.451.9655