2 x 300Gb disks only give 550Gb array ? 1

[rpreston]

I am installing Win2000Adv server on a HP Proliant DL360.

I have 2x300Gb U320 drives, installed as a single volume at RAID0. This gives me a total volume size of just over 550Gb. Where's my other 50Gb gone ? 10% seems to be a large amount of disk space to lose ?


TIA



Rob

 

[fraxx]

First things first, are you absolutely positevly without a doubt you want raid0? Lose one of the disks, you lose all data. I always mirror the disk, raid1.

But to answer your question:
Lets see, 2x300GB, is actually 2x 300.000.000.000 bytes. All drives are specified like this.

However, in Windows (and most other OSes I believe) a GB is defined as 1024^3=1.073.741.824 bytes. This means you actually have 2x300.000.000.000/1.073.741.824 = 558GB. Take away some NTFS overhead, and there you go.

 

[rpreston]

Fraxx,

Thanks for the info. This ties in with what I've since found out from other sources.

However, this confuses me slightly. As far as I'm concerned, 1Kb=1024b, 1Mb=1024Kb, 1Gb=1024Mb. It's always been my understanding that this is the case, and all literature I've ever read and everyone I've ever spoken to on the subject seems to have the same opinion.

If that's the case, how on earth do manufacturers get away with selling you a 300Gb drive that doesn't actually contain what is officially 300Gb ????

 

[fraxx]

In the strictest of sense: k means kilo means 1000, mega means million means 1.000.000, giga means billion means 1.000.000.000. Tera means trillion means 1.000.000.000.000 etc.

We just have to accept that the defacto standard for specifying drive capacity uses these values for the latin prefixes, whereas operating system does not. This has always been the case, but has only become obvious the last few years when capacites have increased so much.