RE: Configuration of the SAN

  • From: John Kanagaraj <john.kanagaraj@xxxxxxx>
  • To: "'lucdemanche@xxxxxxxxx'" <lucdemanche@xxxxxxxxx>, oracle-l@xxxxxxxxxxxxx
  • Date: Tue, 29 Mar 2005 09:05:12 -0800


Although I am a member of BAARF ( - Member number 18, just
squeaked in before Anjo!), I do realize the realities on the ground as far
as RAID 5 goes. Your Redo logs should multiplex on the two LUNs, but you do
need to use the third for TEMP. The archive logs can be part of the same two
LUNs as can your Stage-to-Disk, Binaries, not-so-often read directories,
etc. On our very active Oracle Apps database, we have a three LUN RAID1
config allocated specifically to redo logs, archives, certain small never
read tablespaces etc. We have not faced any redo perf issues. In fact the
multiplexing saved our collective bottoms when an otherwise-excellent SA
deleted the files from one filesystem that contained the online redo logs.
We are able to recover without data loss only since we were multiplexed. The
bottom line is that I would rather half-fill a very large filesystem that is
otherwise not used with something that I know about rather than have a
'smart' SA allocate some very busy files on my previously "exclusive"

John Kanagaraj <><
DB Soft Inc
Phone: 408-970-7002 (W)
Fear connects you to the Negative, but Faith connects you to the Positive! I
Jn 4:18
** The opinions and facts contained in this message are entirely mine and do
not reflect those of my employer or customers **

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Luc Demanche
Sent: Tuesday, March 29, 2005 8:41 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Configuration of the SAN


We are trying to do a good configuration of our SAN.
Let's see that exemple.

EMC, with disk of 146G.
- one LUN of RAID-5 for data (4+1 disks = 534G)
- one LUN of RAID-5 for index (4+1 disks = 534G)

Here is my question, about redo logs
- one LUN of RAID-1 for redo group 1 (2 disks mirroired = 146G)
- one LUN of RAID-1 for redo group 2 (2 disks mirroired = 146G)
- one LUN of RAID-1 for my archived log files (2 disks mirroired = 146G)

I will have a filesystem of 146G to store my redo group of 2G .... what a
Same thing for my redo group 2 and my archived log files ...

What is your LUN configuration regardinf redo log groups and archived log
files ?

Thank you

Luc Demanche
Oracle DBA
(514) 867-9977

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