Expand MSA 1000 LUNS and LUN structure?

[Kimik]

Is it possible to add new physical disks and expand an Array on an MSA-1000?

Also, Something we've come to realise is that perhaps the MSA-1000 is missing an important layer of configuration, in that each array effectively corresponds to a single LUN. Our ideal configuration would be to have for example, an array that spanned 14 physical disks and then several LUNS inside that.

There seems to be no way to do this with the MSA 1000. Every array is a LUN, and we have to rely on guest partitioning - but partitions aren't LUNs, and our ESX servers like to see separate LUNs!

[Uwe Zessin]

Yes, it is possible to add new physical disk drives to an MSA1000. Yes, it is possible to expand an array to include more disks.

No, you are wrong. The layer is there: it is called a 'logical disk'. You can put multiple logical disks into a disk drive array on the MSA1000.

[Kimik]

From the CLI doco - "A LUN is a logical storage unit comprised of one of more hard drives".

When I create the LUN using ADD UNIT, I also give the LUN a RAID level and also add any spares to the LUN.

My thinking is that we should create the array with RAID characterstics and spares, and then create the logical units inside the array. The LUNs should then be presented to whichever guests are attached, right?

[Uwe Zessin]

But your thinking is wrong.

The RAID level is a characteristic of a logical disk, not the disk array. When you work with the CLI, you just don't see the disk arrays unlike when using the ACU.

See the "SIZE=" option for the "ADD UNIT" command. With the first command you implicitly create the disk array, but you don't need to allocate all of its size. Another "ADD UNIT" command specifying the same set of disks creates another logical disk inside the same disk array.

But watch out! You can only delete logical disks in reverse order.

[Patrick Terlisten]

On the MSA1x00 you group harddisks into arrays. In these arrays you create LUNs with a specified RAID-Level. An array can hold more than one LUN. If you add new disks to an array, the added space can be used to expand one or more LUNs on that array. In the end the LUNs are presented to the host, not the arrays.

Regards,
Patrick

[Kimik]

Thanks for the knowledge. I think part of the problem is just the terminology HP have used.!

I understand much better now.

[Uwe Zessin]

Yes, I agree. Especially the usage of "LUN" comes up in many, erm, entertaining ways...