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Re: Optimal Disk Layout??

From: satar naghshineh <>
Date: Fri, 21 Sep 2001 12:23:51 -0700
Message-ID: <>

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.


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Author: satar naghshineh

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Received on Fri Sep 21 2001 - 14:23:51 CDT

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