Re: ASM setup

From: hpuxrac <>
Date: Mon, 28 Apr 2008 16:27:00 -0700 (PDT)
Message-ID: <>

On Apr 28, 1:18 pm, macdba321 <> wrote:


> Thanks for the reply! I actually just got the book you recommended and
> since (for once) I have some spare time and some spare hardware, I'm
> playing around with it as I read along.

The book is pretty good. Definitely written by the people that designed the software.

> Regardless, since this is all 100% for fun/academic, a quick question:
> If you were setting up a server/database for 100% speed (ie, ZERO
> requirements for HA and/or disaster recovery .....if I lose a drive,
> oh well, I start over, etc.):
> (The server has 3 raw disks)
> Would you:
> A) Hardware-based RAID-0 the 3 disks and let ASM see them afterwards
> as 1 "device"
> B) Oracle-based RAID-0 the 3 disks
> C) Don't use RAID at all
> D) Other????
> Thanks, and again, this is 100% academic/fun .... this is ZERO
> requirement for High Avail!!!!!!!!!!!!!!!!!!!!!!

Vladimir has a good point about the online logs. You can isolate them on 1 disk ... either an ASM disk or file system based ( if you were running unix/linux then a direct raw partition is one option ) ... you can in other words mix and match some parts of the database asm but others not.

For the other 2 disks why not lie to asm and tell them they are external redundancy. So create a diskgroup that has just those 2 disk as external redundancy. Now when you create tablespaces on it asm will alternate extents between the 2 disks. In other words, you can use raid 0 to stripe or you can view them as 2 disks and let asm do that part.

What you really need is about 7 (or more) disks. Use 2 for the online logs in archive log mode so when you write to one, you then switch logs, write to the other while the first online log is being archived to disk 3. Then setup disks 4, 5, 6, 7 as disks in an external redundancy log group but just allocate part of the disks ( outer cylinders ) for best IO performance. ( Take your server admin out to lunch ... by them an itunes gift certificate and bingo ... more hardware appears eh? ). Received on Mon Apr 28 2008 - 18:27:00 CDT

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