Sun T4 Storage Arrray and BAARF

  • From: "MacGregor, Ian A." <ian@xxxxxxxxxxxxxxxxx>
  • To: "ORACLE-L" <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 4 Aug 2005 07:20:44 -0700

SLAC has used Sun Storage devices for many a year.  Due to flexibility 
requirements  databases associated with experiments are provided with their own 
server.   Due to space requirements, I've always divided a Storedge array thus: 
 Two disks, total as a RAID 10, the rest of the disks save one as a RAID 5 
stripe, and the last disk as a hot spare.  Online redologs go on the mirrored 
portion, and the data,  rollback,  temporary, and other segments are placed on 
the RAID 5 stripe.  A group of online redologs is also "duplexed" off the array 
to internal disk.  Archived logs are also written to another internal disk.

This has worked fairly well.  The main excepetion being large hash joins.  With 
a T4 array and its 14  ~140 GB disk, I can possilbly use RAID 10 for both the 
online redo logs and the various segments.  I'm not sure if that will result in 
better performance.  There is advice to use RAID 5 if 90% or more of the 
operations are reads and 10 if not.   I don't know the distribution of reads 
and writes.  


RAID 5 has worked well for us.  The one notable exception is large hash joins 
which may do a large number of direct writes to temporary segments.

What are others with T4's doing?

Ian MacGregor
Stanford Linear Accelerator Center

Ian MacGregor
Stanford Linear Accelerator Center
ian@xxxxxxxxxxxxxxxxx
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