Most of time you end up thinking that we had 500 GB disk but it finish without utlizing full capacity. Answer for this that whatever size you buy you do not get full amount of size becuase DMX size calculation on cylinder basis. Lets understand how DMX calculation size of disk:

**1) How DMX 2 and Symmetrix Covert cylinder to GB?**

GB = Cylinders * 15 * 64 * 512 divided by 1024 * 1024 * 1024

for example 18570 cylinders is 8.5 GB

**2) How DMX 2 and Symmetrix Covert GB to cylinder?**

Cylinders = GB / 15 / 64 / 512 then multiply result by 1024*1024*1024

**3) How much capacity do I get from a drive ?**

This depends on the drive and splits required.

For example a 73GB drive with 8 splits gives 8 x 18570 cyl volumes = 68 GB.

**4) How DMX 3 Covert cylinder to GB?**

GB = Cylinders * 15 * 128 * 512 divided by 1024 * 1024 * 1024

for example 18570 cylinders is 17,00 GB

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**5) How DMX 2 and Symmetrix Covert GB to cylinder?**

Cylinders = GB / 15 / 128 / 512 then multiply result by 1024*1024*1024

**6) How much capacity do I get from a drive ?**

This depends on the drive and splits required.

For example a 73GB drive with 4 splits gives 4 x 18570cyl volumes = 68 GB.

Now, you must have understand the formula of calcuating the actual size of disk you can use on any symmetrix or DMX.

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Great, what about DMX4-950?

How do you do the same for a DMX4-950?

DMX-2 was a LOOOOONNNNNGGGGG time ago! This calculation has since changed.

GB = Cylinders * 15 * 64 * 1024 divided by 1024 * 1024 * 1024

Cylinders = GB / 15 / 64 / 1024 then multiply result by 1024*1024*1024