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## XP12000 & CU Question

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## XP12000 & CU Question

We recently had some additional disks added to our 12k. Rather than installing them in the existing CU0 - CU3 slots they created new CU's going from CU4 - CU6. My question is simple, what is the most number of ldevs allowed in a CU? It appears that the number is 256 but would like someone to validate that answer.

We are running OPEN-E 3+1 if that matters.

Sorry if this has been answered or is in some HP document but I googled for it and found nothing and if google can't find it who am I to think it exists! ;-)

Thanks for your time and kind responses.

hb
4 REPLIES
Trusted Contributor

## Re: XP12000 & CU Question

According to my Class room documentation, the XP12000 can hold the following:
DKC (R0) = 128 disks
L1 = 256 disks
L2 = 256 disks
R1 = 256 disks
R2 = 256 disks

Maximum Number of Disks = 1152
Slotes Reserved for Spares = 8
Maximum Number of Spares = 40

Rob....
IF you do it more than twice, write a script.
Respected Contributor
Solution

## Re: XP12000 & CU Question

Hi Hollis,

You are correct, the maximum number of LDEVs that can be mapped into a CU is indeed 256. It does not matter what emulation type you are using such as OPEN-E nor does it matter what RAID type such as 3+1 as you have stated in your example.

The response you got just above from another person is nothing to do with CUs nd could be misleading. DKCs, DKUs etc are physical components of the 12K that hold the disks and other physical components.

A CU (Control Unit) on the other hand is purely logical and used for addressing logical volumes (LDEVs). It is a map that exists in shared memory.

Hope this helps,

Nigel
Talk about the XP and EVA @ http://blog.nigelpoulton.com
Occasional Visitor

## Re: XP12000 & CU Question

Awesome, thanks!
Honored Contributor

## Re: XP12000 & CU Question

BTW:
I strongly recommend migrating from Open-E to Open-V on the XP12000.

The XP12k is optimized for Open-V.

1. Performance of Open-V is much better due to Cache optimization
2. Certain features of the XP12k only work with Open-V

Cheers
XP-Pete
I love storage