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Array Expansion on a Dell PowerEdge Server with a Perc3/DC controller

Novell Cool Solutions: Trench
By Lee Phillips

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Posted: 15 Sep 2004
 

The overall objective of this procedure is for a single volume (example SYS:) to be expanded when additional drive(s) are attached to a server and the existing RAID 5 array is expanded to incorporate these new drives.

On a Dell PowerEdge server running a Perc3/DC Array controller, you insert the new drive(s) and bring up a utility called dellmgr.nlm that will expand the existing array to incorporate the new drive(s). This utility expands the existing array to incorporate the new drives and expands the existing logical drive with the new space. A tool such as Symantec's ServerMagic can be used to expand the existing NetWare partition. The NetWare utility install.nlm will be used to expand the existing volume (example SYS:) to use the additional free space.

The end result of these is an ?On-Line? Array expansion.

  • Advantage - The user only has one logical drive to work with after the expansion.
  • Disadvantage - One reboot is required after ServerMagic is run.

If you have any questions you may contact Lee at lee_phillips@dell.com

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Geoffrey Carman

I have a comment on this article. I also posted it as a Reader's Comment on that page. I am adding some more info in this email now that I thought about it more.

In Dellmgr.nlm (not there if you did the default NetWare install from the CD's and did not get a Dell driver set), the menu option you are looking for is called Reconstruct. You select the logical drive and the new disk to add into it, (space bar to select, enter to end array addition). It takes many hours to reconstruct, depending on size, speed, and number of disks, as you would imagine. As of NetWare 5.x and higher you are allowed multiple NSS and TFS partitions on one logical drive. Which means you could just create a new TFS or NSS partition to handle the extra space. NSS Pools can span multiple partitions.

If you have Dell's FlexRAID Virtual Sizing set to ON, you will have a problem with NetWare higher than 4.2. In fact your only option is to recreate the logical drive. If you turn OFF FlexRAID in the BIOS (Ctrl-M at boot time, menu looks the same as in DellMgr.nlm) then the data seems to disappear. If you immediately turn FlexRAID back on, the data will be 'back' on your next reboot.

This basic info is true for all the AMI/LSI based PERC controllers. (PERC, PERC II, 2DC, 2SC, 3DC, 4DC, 4Di) but not for the Adaptec based PERCs (2Di, 2QC, 3Di and many more models) which work entirely differently.

PERC Firmware revisions are very important. Keep up to date. Dell has posted at least two updates that resolve potential data loss issues.

The PERC 3DC also has an odd problem with fragmentation in the RAID Stripe set. A BIOS update (1.74 at a minimum, but newer is out now) resolves the issue, but requires a consistency check to be run. (DellMGR, Check Consistency, select logical drive. It will take many hours, and degrade performance during the operation.) It will repair errors, but will not report them. One of the symptoms seen is the inability of a 2-node shared SCSI cluster to mount the SBD partition on the second node. Whichever node is mounted first will work, the second one will not mount it, and thus will not join the cluster.

If you have any questions you may contact Geoffrey at geoffc@Yorku.ca


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