Raju, I believe section 4.6.9 in that Redbook describes what you're seeing:
<start quote> When the arrays are created on a DS8870, the microcode determines which array sites contains spares. The first array sites on each DA pair that are assigned to arrays contribute one or two spares (depending on the RAID option) until the DA pair has access to at least four spares, with two spares placed on each loop. A minimum of one spare is created for each array site that is assigned to an array until the following conditions are met: There are a minimum of four spares per DA pair. There are a minimum of four spares for the largest capacity array site on the DA pair. There are a minimum of two spares of capacity and RPM greater than or equal to the fastest array site of any capacity on the DA pair. <end quote> So you might need to create some other arrays before you create the arrays where you don't want spares. Your local IBM storage engineer should be able to help you plan your configuration. Bart -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Raju Reddy Sent: Friday, February 15, 2013 8:48 AM To: [email protected] Subject: Re: DS8870 - RAID 5 issue Scott, Thanks for that.. I have the Redbook handy and followed the same procedure. But there it is mentioned how to use RAID 5 (7+P) combination. And also while creating Arrays, I dont see RAID 5 (7+P) but it automatically pick ups RAID 5 (6+P+S). Regards, Raju On Fri, Feb 15, 2013 at 1:01 PM, Scott Ford <[email protected]> wrote: > Raju, > > http://www.redbooks.ibm.com/abstracts/sg248085.html?Open > > Scott ford > www.identityforge.com > > Tell me and I'll forget; show me and I may remember; involve me and I'll > understand. - Chinese Proverb > > > On Feb 15, 2013, at 3:26 AM, Raju Reddy <[email protected]> > wrote: > > > Dear All, > > > > We are under the process of migrating to DS8870 from DS8810. > > > > While I create new Ranks with Array capacity of 2400GB(8*300GB), I get > > around 1652GB of usable storage while rest will go for Parity and Spare. > > > > We use SSD disks and I used Ranks to pick RAID5 which automatically > picked > > RAID 5 (6+P+S) and thus causing loss of 750 GB of storage. > > > > We need RAID 5 (7+S) for 'Development' LPAR's to increase the usable > > storage but DS8000 GUI is not allowing me chose RAID 5 (7+S) combination. > > > > Can you please advice how to make Ranks pick RAID 5 (7+S) combination.? > > > > > > Regards, > > Raju ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
