Summary: Disk capacity

From: Chiles, Keith # IHPLS <KChiles_at_hccsf.com>
Date: Fri, 14 Nov 97 11:46:26

     Dear Netland,
     
     I was asked to summarize my posting regarding the disk capacity
     problem I was having trying to see a 45 GB disk array through the
     SWXCR controller.
     
     It turns out that there is about a 30 GB limit to a logical device in
     the SWXCR controllers. This requires me to create and initialize two
     logical devices to get the whole 45 GB. I will try to put the device
     on a F/W controller and off the SWXCR.
     
     For those who asked, I was not running a F/W SWXCR controller because
     there were none certified when we established this configuration. We
     put the 3 channel SWXCR's in the system as the only means of having a
     supported configuration. We then ran our disk arrays as JBOD.
     
     The reason I didn't discover these problems earlier is that we just
     upgraded from 20 GB to a 45 GB array. I was replacing logical device
     zero, but had some RZ29's configured as RAID 5 arrays using logical
     device 1 and 2.
     
     My mistake was that I just upgraded the JBOD drive to 45 GB and
     initialized it. I didn't delete the original JBOD definition because
     it would require that I rebuild all of the other RAID 5 arrays and
     play with tape. I initialized the 45 GB drive, but the logical device
     definition in the SWXCR controller remained at 20 GB, the size of the
     original JBOD device.
     
     What did I learn? When we create a logical drive, the SWXCR
     controller appears to query the drive to get its capacity. It then
     records the capacity of the drive in the SWXCR controller, even if it
     is JBOD. Initializing the logical device simply reads the
     configuration in the SWXCR controller and doesn't requerry the device.
     When building a label for the logical device, the disklabel command
     querries the device, but instead of querring the actual disk, it gets
     a response from the SWXCR controller that tells it the disk capacity
     at the time the logical device was created, not when it was
     initialized.
     
     Moral of story. You have to go back and wipe out all arrays to get to
     the bottom one, even if it is JBOD. How nice, because I'm still out
     of production while the SWXCR initializes what is now about 80 GB of
     drives.
     
     My thanks to those who responded, Keith
Received on Fri Nov 14 1997 - 21:50:52 NZDT

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