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Maximum Size on 12H AutoRAID Array

Premgy Varghese
Occasional Advisor

Maximum Size on 12H AutoRAID Array

I have a 12H AutoRAID storage attached to my HP-UX 11.0 server.

The 12H has 12 x 17366MB disks.
Total physical = 208397 MB
Allocated to LUNs = 158120 MB

What is the maximum allocation to LUNs possible with the current disks?

Thanks
Premgy
3 REPLIES
Torsten.
Acclaimed Contributor

Re: Maximum Size on 12H AutoRAID Array

IMHO this is already the maximum, more or less. All other space is used for redundancy. Remember, the array is doing raid0+1 or raid5 (both at the same time = autoraid).

Hope this helps!
Regards
Torsten.

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Bill Hassell
Honored Contributor

Re: Maximum Size on 12H AutoRAID Array

The 12H autoraid is a first generation smart array that moves data around between RAID levels to optimize speed and reliability. The 12H performance is directly related to how much of the total disk area is actually used (written). As usage increases to more than 50%-60%, performance drops quite rapidly. This is by design and can't be changed.

The 12H was a pioneer in smart arrays but it is archaic by today's standards. Replace the 12H with a relatively mature VA -series and you will see 10x-15x performance increase.


Bill Hassell, sysadmin
Victor Fridyev
Honored Contributor

Re: Maximum Size on 12H AutoRAID Array

Hi

It seems to me that 12H is the second version of this kind od storages (BTW, excellent thing !)
If yoy run arraydsp -a SERIAL_NUMBER, you'll see something like this:
--- Disk space usage --------------------
Total physical = 208397 MB *
Allocated to LUNs = 143084 MB *
Used as Active Hot spare = 17366 MB *
Used by non-included disks = 0 MB *
Used for Redundancy = 32313 MB *
Unallocated (avail for LUNs) = 15634 MB *
-----------------------------------------

AFAIU, Allocated to LUNs + Unallocated (avail for LUNs) gives you desired result.
Bill is right re performance degradation with zero unallocated space, but if you need disk space and don't have a money to buy a new cheap SCSI storage ....

Good Luck
Entities are not to be multiplied beyond necessity - RTFM