Re: Physical Layout of disk to use Oracle

From: Hari Om <hari_om_at_hotmail.com>
Date: 18 Sep 2003 09:34:39 -0700
Message-ID: <d1d5ebe4.0309180834.3dc0ecb6@posting.google.com>

Thanks Howard.....HATS OFF to you.....that was really a good advice....
(BTW, I also got the difference betwee members and groups...)

Here is my advancement:

disk0 --> AIX + SYSTEM TBLSP + Control File1
disk1 --> AIX + SYSTEM TBLSP + Control File1
disk2 --> REDO Log Files 1a,1b,1c + Control File2
disk3 --> REDO Log Files 2a,2b,2c + Control File3
disk4 --> ARCHIEVE + TEMP + Oracle SW

RAID 5 (disk5+disk6+disk7) --> DATA + UNDO

what do you think...is it better approach then my previous version....?

Note: Disk2 + Disk3 are each 36GB ...so do you think I am UNDERUTILIZING those disk.....?

Also, I have pushed SYSTEM TBLSPC to my MIRRORED disk0/disk1 combination....would there be any issues in that.....? Do I need to MIRROR SYSTEM TBLSPC also.....? In your last reply you mentioned SYSTEM to be in RAID 5 along with DATA....is that OK...? I read somewhere that SYSTEM "should be" separate from DATA.....correct me if I am wrong.

Any better approcah then this one is welcome....THANKS Howard.

HARI OM "Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message news:<3f68dd14$0$28117$afc38c87_at_news.optusnet.com.au>...
> Hari Om wrote:
>
> > Hi Howard,
> >
> > What about this approach. I have two 18GB hdisk (mirrored with OS
> > installed on it) and SIX 36GB hdisk.
> >
> > It seems that since SYSTEM and REDO Log files are "NOT GOOD" for
> > RAID 5, I came up with following. Instead of RAIDing (level 5) on 6
> > hdisk I would RAID only 3 disk and use them soley for DATA files.
> > So here is my layout:
> >
> > hdisk0 --> AIX OS + Control File1 + Redo Log (Group 1)
> > hdisk1 --> AIX OS + Control File2 + Redo Log (Group 2)
>
> I take it these are the two 18GB hard disks, in a RAID0 (mirroring) setup.
>
> Good, Redo Logs will do well on a RAID0 setup, but they won't appreciate
> sharing that with the operating system.
>
> But your redo log configuration looks a bit dodgy anyway. Either that, or
> your terminology is wonky. Redo log *groups* can all share the same hard
> disk (leaving aside archiving issues at the moment). You need at least two
> *groups*. Each group should then have multiple *members*, to prevent
> software or user corruption. hdisk0 can therefore have 2 redo logs on it,
> and those will be mirrored onto hdisk1. But that still means, from Oracle's
> perspective, that you only have 1 member per group. LGWR writes only once,
> and your mirror ensures its write is replicated to hdisk1. Which is better
> than a kick in the teeth, but what happens if you accidently practice your
> 'rm *' skills one day? Er, you lose the log on both disk0 and disk1...
> total loss of redo logs, and hence lost data.
>
> Somewhere in your scheme, you need to make provision both for redo log
> mirroring (good for protection against hardware failure), which is what it
> would seem to me your hdisk0/hdisk1 mirror would provide. And for redo log
> member multiplexing... which you don't appear to have in this proposal at
> all....
>
> > hdisk2 --> Oracle SW + SYSTEM Tablespace files
> > hdisk3 --> REDO LOGS (Group 3)
>
> ...although hdisk3 could well be a candidate for the second *member* of all
> your groups. (In other words, get the difference between groups and
> members sorted before you go much further).
>
> > hdisk4 --> ARCHieve Log Destination + UNDO
>
> Why have you separated out UNDO?
>
> Can I make one suggestion? Put down the Loney book, and stop trying to match
> his suggestions (which are valid only for non-striped, non-RAIDED systems).
>
> UNDO is a tablespace. It has datafiles. Datafiles, in your plan, belong on
> the RAID5 set. So stick the UNDO in there.
>
> > RAID 5 Disk (hdisk5 + hdisk6 + hdisk7) ---> DATA Files + TEMP
> >
> > I cannot put my "hdisk3" under RAID 5 becos to Ohdisk0 --> AIX OS +
> Control File1 + Redo Log (Group 1)
> > hdisk1 --> AIX OS + Control File2 + Redo Log (Group 2)S RAID 5 is just one
> > LOGICAL DISK and so I cannot multiplex them on different disk.
>
> See above. You appear to me not to grasp the distinction between members and
> groups.
>
> > Will there be any issues in above setup....? Does someone here nay
> > better idea then this one....?
> >
> > THANKS!
>
> This isn't ideal, because of the logs+O/S issue, but try this:
>
> hdisk0 --> AIX OS + Control File multiplex A + Redo Log Group 1, 2 and 3,
> member A
> hdisk1 --> AIX OS mirror + Control File Mirror + Redo Log Group 1,2,3 mirror
> of member A
> hdisk2 --> Archive Redo Logs
> hdisk3 --> ControlFile multiplex B + Redo Log Group 1,2,3 Member B
> RAID 5 Disk (hdisk4 + hdisk5 + hdisk6 + hdisk7) ---> DATA Files + TEMP +
> UNDO + SYSTEM
>
> But it all rather depends on the number of controllers you've got, as well
> as hard disks.
>
> Regards
> HJR
Received on Thu Sep 18 2003 - 11:34:39 CDT