Formating for a 146GB SCSI drive

[Rhino_1]

Hello,

I have a 146GB Ultra3 SCSI drive. The array controller sees it as 140GB after I create it as a logical drive (Raid 0). Windows 2003 server sees it as a 136GB drive.

Why am I loosing 10GB of space in this process. I can see having some overhead and loosing a few gig but 10 seems too high. What am I missing?

Thanks,

[Rhino_1]

Just to add some more info... This is in a DL360 server with a Smart Array 5i controller.

[Jefferson Humber]

Rhino,

To begin with the HDD manufacturers call a Gigabyte something different to the rest of us. To them 1Gb = 1000Mb, when the rest of us know 1Gb is actually 1024Mb.

Next up there's the RAID overhead of creating the array. Then on top of that you have the file system overhead when you format the drive, probably NTFS in your instance within the O/S.

You will never get what it says on the HDD as usable space, you always loose a few percent when all these overheads are added together.

Hope this helps,

Jeff

[Rhino_1]

Thanks for the reply. I agree with and understand all of what you are saying....but 10 gig seems like a lot to me. Am I off base with that? Can anybody confirm that I should only be seeing 136 GB in Windows 2003 on a 146 GB drive?

Thanks for your help.

[Jefferson Humber]

The real size of the HDD is probably nearer 142Gb (due to the 1024Gb/1000Gb conversion), so only seeing 136Gb in Windows is not out of the question in my opinion...... especially when you add the RAID & NTFS overhead into the mix on top. I reckon you've probably only lost approx 4% through these two overheads.

[Uwe Zessin]

Hardware (146GB) and Software (136GB) Gigabytes are just different expressions of the same capacity. There is nothing 'wrong' or 'right' and you are not 'loosing' 10GB.

146000000000 /1024*1000 /1024*1000 /1024*1000 =
135973095000

Let's take another example:
what is the difference between:
10 | 1010 | 0A | 12

or better:
10(10) | 1010(2) | 0A(16) | 12(8)

Answer: there is none!

[Patrick Wallek]

Here is some interesting reading for you.

http://en.wikipedia.org/wiki/Binary_prefix

If you are talking about a GIGABYTE, then that is 1000 MB. However, a new term has been coined, GIBIBYTE, which is 1024MB.

See the section in the link above where it talks about the IEC standard prefixes. What most of us have always called a Gigabyte, is technically a Gibibyte.

So your 146GB drive, is 146,000 MB, or 146,000,000 KBYTES or 146,000,000,000 Bytes.

If converted into it's binary (where 1GiB is 1,024 MiB) then you actually have 146,000,000 KB / 1024 = 142,578.125 Mibibytes. 142,578.125 MiB / 1024 = 139.236 Gibibyptes.

So, technically you are not losing as much as you think.

There have apparently been some lawsuits against major manufacturers about inflating their HDD capacity claims. See the footnotes in the link above for information.

[Rhino_1]

Thank you for all of the responses. It is nice of you to do all of the math for me....lol