How to calculate the real size of the ESXi 5 VMFS volume?

[k1222s]

I have a HP MSA2040 600G*5 disk for a Raid5.When I create a Volume (2299.9GB),and I add volume to ESXi 5 datastore,it config and show 2.09TB result.

Why does it so much difference?

****I Know ESXi 5 VMFS5 block size (1MB)****

Who can calculate the capacity size(2.09TB)and tell me?

[RyanH84]

Hi,

I think this is because that when you have created your RAID5 volume, you have combined your 6 disks into one big lump of storage.

5*600GB = 3000GB of "advertised" disk space.

If you take what you have after RAID5 with (n-1) you get 2400GB of "advertised" disk space. (In reality this is going to be closer to 2299.9GB).

Now, when you format the disk with VMFS-5 you are formatting 2299.9GB of raw space presented to the OS. This is the advertised amount of storage you have as a decimal value. The system will be showing the binary representation of this, after formatting and such.

So taking this explaination into account you can work out:

Your storage amount * 0.9094947 = Your final useable storage

2299.9 * 0.9094947 = 2091.74686053TB

= 2.09 TB

I hope that makes sense?

[a_p_]

As already explained by RyanH84, the MSA - by default - shows the "marketing" disk space, i.e. the base-10 size (GB) rather that the real, technical base-2 size (GiB).

Please take a look at HP Support document - HP Support Center for detail, and how to switch to the base-2 representation.

André