RAC and ASM disk layout

  • From: "Daiminger, Helmut" <HELMUT.DAIMINGER@xxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 9 Jun 2006 12:41:43 +0200


We are new to RAC and are discovering serveral uncertainties regarding
the best disk layout to use for ASM. We are running two EMC Clariion
systems (under RAID-5) and want ASM to write to both Clariions
simultaneously (i.e. use normal redundancy). ASM will balance the load
across the two failover groups (i.e. two LUNs) which reside in two EMC
Clariion arrays.

The question is, whether it is better to use a single LUN with 100 GB or
have a number of smaller LUNs (totalling 100 GB). Since we are using a
single raid group (i.e. 5 disks) for all database storage, all LUNs will
end up on the same physical devices anyway. So it might be harmful
having ASM to try and balance I/O across several LUNs which all reside
on the same physical devices.

This is 10.2 on HP-UX 11.23.



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