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Expanding a Mirrored Volume in a Two-Node Cluster

Novell Cool Solutions: Feature
By Jack Shreve

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Posted: 29 Nov 2007
 

PROBLEM:

This is a step-by-step, How-To instruction on expanding a mirrored volume in a two-node cluster, aimed at administrators without a lot of clustered/mirrored data pool experience.

The situation is you have a two node Novell cluster, with mirrored iSCSI storage running on two Netware servers (not quite real SANs, but common enough)

One of your resources has run out of space, and you have half a dozen emails/help-desk tickets from concerned users that have received the "...Volume/(or Pool) XXX is almost out of disk space/is out of disk space" broadcast message.

SOLUTION:

This assumes you have unallocated space on your cluster data partition. If not, you will need to add disks.

Let's Begin:

To Expand a Clustered, Mirrored Volume:

At the system console of the server presently hosting the resource that is running low/out of disk space, invoke the Novell Storage Services Menu Utility by typing (Do not include quotes):

"NSSMU"

Scroll down to "Pools" and hit "Enter".

Highlight the pool that hosts your desired volume and press F3, which is "Expand".

If, upon highlighting that pool, F3 does not appear as an option on the bottom of your screen, and pressing F3 does nothing, one of two things is true. Either you do not have any space available to expand this pool/volume, or you are not on the server hosting the volume/pool you want to expand.[Helpful hint: Watch the bottom of the screen in NSSMU and it will tell you what actions are available]

Assuming neither of the above is true, a list of ALL partitions' available space will appear, including space on your SBD -Split Brain Detector - partitions. This SBD partition set will be in MB rather than GB. DO NOT USE.

There should be at least two identical partitions displayed big enough to use; they should be the same size, or you may have an indication your mirrord SANs are out-of-whack.

Of the available partitions that are large enough to accommodate your desired expansion, write down the ID's (e.g., P:0x23) of both the identical partitions. Make a note of the one you are going to select. It is actually an arbitrary decision as to which one you select, so pick the top one.

Press Enter.

By default, you will be presented with the entire free space available on that partition. If you do not want to allocate the entire free space to this pool/volume, type in how much space you want to use, and press Enter.

NOTE: If you have other volumes that might need expansion from this same data partition, reserve space for them. However, don't make the mistake of taking too small a piece of available space. The downside of taking small "bites" of available space is that the more segments a volume has, the more complex management gets, and the more likelihood failure or accident becomes- especially due to misbehaving 3rd party NLMs or database apps. So try to balance future needs for this volume against the possibility other volumes will need to grow.)

Now, ESC out to Main Menu, and select Partitions.

Scroll through the list looking for the ID you noted earlier; it will be one that has "Mirror ID: None".

Ignore DOS, SYS, SBD partitions.)

Highlight it, press "Enter". and Press F3 to mirror it.

Only partitions large enough to mirror your choice will appear. If there are more than one, look for the one with the other ID you wrote down.

Press Enter, then flip to the system console screen.

The message "... remirroring..." should be there.

Close NSSMU.

Environment:

Netware Cluster Services.
NW 6.x


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