RE: Mirroring redo log groups or not ?

  • From: "Crisler, Jon" <Jon.Crisler@xxxxxxx>
  • To: "Rajeev Prabhakar" <rprabha01@xxxxxxxxx>
  • Date: Tue, 7 Apr 2009 13:14:12 -0400

The redo logs are 6 groups, 2 members each, 1gb in size.  The SAN is EMC
Clariion.  Raid 5 does have somewhat poorer performance in writes in our
environment but its usually not a major factor.

-----Original Message-----
From: Rajeev Prabhakar [mailto:rprabha01@xxxxxxxxx] 
Sent: Tuesday, April 07, 2009 12:48 PM
To: Crisler, Jon
Cc: Oracle-L Freelists
Subject: Re: Mirroring redo log groups or not ?

Hello Jon,

Before you go into redesign of the redo logs, did you check w/the
Admins ? During my last interactions with type of performance issue, I
that RAID 5 had a negative effect on overall performance during QA
testing. of
course, your mileage may vary.

Can you share your findings (as seen by SA/Storage Admins). How big are
redo logs ? What kind of disks (Storage/SAN) are you folks using ?


On Tue, Apr 7, 2009 at 12:16 PM, Crisler, Jon <Jon.Crisler@xxxxxxx>

> So, if the LUN that holds the online redo logs is already protected
(raid 1,
> 5 etc) do I really need to mirror the online redo logs ?  Should I
> the LUN to Raid 1 /  0 ?  if I convert to Raid 1/ 0 should I keep redo
> mirroring and point to the same LUN ?

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