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Size calculations on MSA. How to do this

Occasional Advisor

Size calculations on MSA. How to do this


I am designing an new environemnt for our customerwho is using MSA storage (MSA boxes with SMART controllers, not an MSA2000)
Now I can use the CLI or ACU to configure the storage, but I do need to know the correct way to calculate the sizes and overhead
Assume I have 50 drives. I want to create a set of LUNS of equal size with Raid 5

assumng no more then 14 drives in a Raid5 set I decide to use 5 arrays of 10 drives each
each drive is 300GB

Now how can I calculate what the useable of my LUNs will be when I create them. I need to specify this upfront

I end up with 5 array of 3000GB each
Since in each array 1 drive capacity is used for parity I end up with useable raw capacity of 9 x 300GB 2.7TB

I need ot divide this in qual portions and use a stripe set of x kB

What is the size of the RAID overhead used?
How does Stripe Size affect this (8KB, 16KB)

I quickly tried this and when using half of the indicated space avaialble on the array, I end up with less then half for the second LUN, so something must be used as MetaData which is not shown upfront

Honored Contributor

Re: Size calculations on MSA. How to do this

You may want to use HP StorageWorks Sizing tool available at

Occasional Advisor

Re: Size calculations on MSA. How to do this

Using this 'tool'does not deliver what I need.
It has poor support for MSA1000
And I could NOT find asnything in there for LUN sizes, just for sizing the MSA array and what to order

I have the boxex I have the disks. The MSA are connected to as P800, and now I need to figure out who sizes are calculated
The drives are 300GB, but this is base 10
ACU mosdt likely calculated using Base 1024
Creating an array uses metadata on the disk, who much do I lose?
Creating LUNs may or may not cause additional metadata space.
How does the stripe size affect the size of LUN.
When I havr an array with 2.7TB of space and create a LUN of 1.35TB the remaining space does not add up to 1.35TB which is strange

Strikpesize of 4KB is no available, 8KB is the smallest...

Again all of this I can not find in the Sizing Tool..... I do not think the Sizing tool support P800 or other Smart Array cards with MSA60/MSA70 enclosures