5300 array/volume expansion problem

[John McFarlane]

I have a Smart 5302-64 with 10 36Gb disks, mounted in a ML530 running NT4 SP6a, I am wanting to make a 330Gb volume. The problem is that the array cannot be expanded past 260Gb, all disks have been added to the array (Raid 5 - 4 disks on one port 6 on the other). Via the ACU the array always reports approx 60Gb free space. I have tried array expansion numerous times and according to the event logs the array has been duly expanded. The machine has been rebooted and no increase in size has been found post an expansion process. Rom revisions for system board, array controller and disks are at the latest version and the ACU is the latest too. Any help would be appreciated.

[Patrick Wallek]

260GB may be all the space that you will be able to have in this configuration.

You will NOT be able to get all 360GB of space (10 x 36GB)to be available to you. Raid 5 by default cause you to lose the space equivalent to 1 disk due to parity data requirements. If you have hot-spare enabled on the array then that would cause you to lose space equivalent to another disk. So that would be 72GB (2 x 36GB), 360 - 72 =288GB. Now that assumes you get all 36GB available from each dish, which you won't due to disk formatting.

I'd say your 260GB number is probably pretty accurate for maximum space in a raid 5 set up like you have.

[John McFarlane]

Further to the original post. Acknowledging the raid/parity overhead, ACU reports that a max permissable size in this config to be approx 330Gb and through the Array expansion option the slider indicates that there is approx 60Gb of free space that can be utilised to expand the array. My problem is that when I move the slider to the maximum size and kick of the expansion process and when this is completed there is no change in array size and the ACU is still reporting that there is 60Gb of free space. Event logs report that:
1. array is expansion mode
2. array is expanding and
3. expansion is complete. (normal time period of approx 6 hours)

When checked in ACU no change has occured to the original volume/array size of 260Gb. Aplogies for lack of clarity in original post.