Re: Am I RAIDed or mirrored

[JDHorn@xxxxxxxxxxxxxx]

   Does this discussion apply to larger strings also.

   we currently have a 520 with 8 disks (70 gig) in 1 parity set separated to
   2 disk pools. (4 in the system asp and 4 in a user asp)

   We are intending to add 6 more disks (70 gig)  into a new parity set. we
   will be adding some of the disks to each asp.

   Is there anything wrong with this scenario?  If we would later add 2 disks
   to the new parity set would we have to reload to get good performance?  If
   we don't reload what are the striping ramifications for the 2 added
   drives?  where does the striping info go in this scenario?

   Jim Horn

   _------------------------------

   message: 5
   date: Sat, 31 Oct 2009 12:36:29 -0400
   from: R Bruce Hoffman <bruce.hoffman@xxxxxxxxxxxxxxxxx>
   subject: Re: Am I RAIDed or mirrored

   You could do that to check to make sure the drive is good. BUT... just
   adding the drive in will not alter the raid striping. What you really
   want is the raid set built on all four drives. The only way I know to do
   that is to reload. If you go to reload and the fourth drive won't light
   up even then, well, that's what the warranty is for... 1-800-ibm-serv
   gets a call for bad hardware.

   IBM did what the order told them to do... 4 drives raid with hot
   standby. That's 3 in raid and 1 standby.

   AFAIAC hot standby really demands at least 5 drives. I always recommend
   4 drives as an absolute minimum.
   ___________________________________________________
   This email is intended only for the person or entity
   to which it is addressed and may contain information
   that is privileged, confidential or otherwise protected
   from disclosure. If you are not the named addressee
   or an employee or agent responsible for delivering
   this message to the named addressee, you are not
   authorized to read, print, retain copy, and disseminate
   this message or any part of it. If you have received this
   message in error please notify us immediately by email,
   discard any paper copies and delete all electronic files
   of this message.