2 Replies Latest reply on Mar 14, 2009 11:34 AM by user10394804

    RAID 1 Vs RAID 0+1

    user10394804
      Hi All,

      My Oracle 11i application (11.5.10.2)'s database is of version 10.2.0.4 and OS is AIX 5.3.

      Our datafile where on RAID 1 configuration (datafile and indexes files on different mount points).

      (In our env ,read and write is almost same ,though read is more compare to write)

      Due to some io issue (hotspot) and better use of space ,we decided to move our datafiles and indexes file on RAID 0+1 confiuration.

      For that we created a volgroup of 4 disk and moved all file to new volgroup.

      Suprisingly,the performance started degrading and that hdisk which contain 5 disk started reaching 100% continously.

      When I was monitoring the topas command,the 'WAIT' which was intially 0 alway started going to 50 as below
      Kernel 2.8 |# | Reads 2593 Rawin 0
      User 71.5 |############### | Writes 871 Ttyout 622
      Wait 19.5 |### | Forks 7 Igets 0
      Idle 17.2 |###########

      Can someone guide me,why this happen?or is it bcz my decsion to move the file to RAID 0+1 was bad one or what?

      Thanks
        • 1. Re: RAID 1 Vs RAID 0+1
          Hussein Sawwan-Oracle
          Hi,

          RAID 0+1 is recommended for database files because it avoids hot spots and gives the best possible performance during a disk failure. It is also recommended you avoid placing Archive Log files on RAID 0+1. Please review the following notes for more details.

          Note: 30286.1 - I/O Tuning with Different RAID Configurations
          https://metalink2.oracle.com/metalink/plsql/ml2_documents.showDocument?p_database_id=NOT&p_id=30286.1

          Note: 148342.1 - Avoiding I/O Disk Contention
          https://metalink2.oracle.com/metalink/plsql/ml2_documents.showDocument?p_database_id=NOT&p_id=148342.1

          I would also suggest you contact your hardware/software vendors for any reported bugs/issues with RAID 0+1 and see if you any patches/fixes are required.

          Regards,
          Hussein
          • 2. Re: RAID 1 Vs RAID 0+1
            user10394804
            Thanks,Hussein