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March 20, 2006

E450 Disk Mirrors

Q: What is the best (most efficient) way to lay out the disks on a Sun E450 (with all disk trays installed)?

A. A fully expanded E450 has 6 scsi controllers which are spread over three dual channel SCSI buses. Ideally these three should be on separate PCI channels (there are also three of these). Given that the on-board SCSI is effectively on channel A, you should put one SCSI card in a channel B slot and one in a channel C slot. Use the "Owners Guide" if you are having trouble working out which slot is in which PCI channel.

Now the six controllers should be:

  • Onboard SCSI controllers (c0 = disk, c1 = media tray)

  • Channel B controllers (c2 = disk, c3 = disk)

  • Channel C controllers (c4 = disk, c5 = disk)

The two tricks to making sure that you have optimal disk performance is simple:

  • Make sure your mirrors ARE NOT on the same SCSI controller or PCI channel.

  • Make sure any RAID strips ARE on the same SCSI controller or PCI channel.

I used to do something like this (for mirrors):

  • c0t0/c0t1 -> c3t0/c3t1

  • c0t2/c0t3 -> c5t2/c5t3

  • c2* -> c4*

  • c3t2/c3t3 -> c5t0/c5t1

Posted by Ozguru at March 20, 2006 06:00 AM