On Thu, Oct 07, 2004 at 02:57:23PM -0700, Sanjay Darisi wrote:
> I've created JFS filesystem on this drive, although XFS would have
> been better for my situation. After creating JFS filesystem, df -h
> shows only 932GB. I was wondering how to get that almost 70GB back. I
> know that in ext2/ext3 filesystem there is a parameter (Reserved for
> super user) that can be tuned. Is there any similar parameter in JFS
> that can be scaled down. 70GB is way too much to loose. Y is 70GB
> unaccounted for in JFS??
No, JFS isn't taking up that 70GB, it's the drive manufacturers
mislabeling their equipment.
Since almost the beginning of computing, this is how computer storage
has been measured:
1,024 bytes = 1 Kilobyte
1,024 KB = 1 Megabyte
1,024 MB = 1 Gigabyte
1,024 GB = 1 Terabyte
(As a side note, notice that 1024 = 2^10.)
Hard drive manufacturers *used* to do this, too. But then somewhere in
the race to be the first to market with a one gigabyte drive, they
started using the following table:
1,000 bytes = 1 Kilobyte
1,000 KB = 1 Megabyte
1,000 MB = 1 Gigabyte
1,000 GB = 1 Terabyte
This subtle-yet-important difference is where your 70GB went. Note the
following chart comparing the way drive manufacturers measure capacity
(right side) with the way everybody else, including your operating
system, does it (left side):
1 byte 1
1,024 KB 1,000
1,048,576 MB 1,000,000
1,073,741,824 GB 1,000,000,000
1,099,511,627,776 TB 1,000,000,000,000
Divide the number on the right by the number on the left and multiply by
1024 to get the actual capacity of your drive/array in the next lower
units. In this case, I get... 931.32257 GB.
There are fine-print explanations of this -- and in more
marketing-friendly terms -- on the boxes the drives came in. They might
say that 1 GB = 1,000,000,000 bytes, or that the 250 GB they claim is
"unformatted capacity".
--
Bill Jonas * bill@billjonas.com * http://www.billjonas.com/
"It's a dangerous business, Frodo, going out your front door. You step
into the Road, and if you don't keep your feet, there is no knowing
where you might be swept off to." -- Bilbo Baggins
---------------------------------------------------
PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us
To subscribe, unsubscribe, or to change you mail settings:
http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
(text/plain)