To partition or not

[Charles Broderick]

On 6/4/03 12:03 AM, "iBook List" <ibook at lists.themacintoshguy.com> wrote:

> It's not enough to matter to me when I've got 40 gigs, luckily.  And back in
> the HFS days of OS 9, you'd actually save space when you had partitions.
> There's a maximum sector (or some such) number, so a file that's 1k might take
> 153k (the smallest unit HFS would handle on a drive of arbitrarily large size)


I am amazed at the useless knowledge I can remember (as opposed to the
important stuff I find so easy to forget).

Back in the day of 16 bit addressing, the most addresses you could address
was 65535 (2 to the 16th power, minus one 'cuz computers start counting from
0). So no matter how big the hard drive was, you could only have 65535 files
on it. When your hard drive was formatted, the Mac would simply take the
size of the hard drive and divide it by 65535, and that was the size of each
sector.

On a 250 MB hard drive, this was no big deal--each sector is about 4k big.
If your file is 4k, it takes up 1 sector, if it is 12 it takes up 3, and if
it is 13k it takes up 4.

The problem was with larger drives, for instance a 1 gig drive. 1 gig is
actually 1024 * 1024 (2 to the 10th power) kilobytes, which is 1,048,576 kb.
Divide that by 65535 and you get 16k per sector. So your 4k file would
actually occupy 1 16k sector, your 12k file would take up 1 sector, and a
17k file would take up 32k (2 sectors).
 
Back in the day when MS word files used to be less than 1MB, (usually only
4k or 7k), this would waste a lot of space! So, people would partition
larger drives to be able to recover some of that valuable space.

Nowadays, you certainly don't need to partition for this reason (I think
they have 64-bit addressing and can address terabytes of info). I find it
conventient to have different operating systems on different partitions--OS
X on one and OS 9 on another, with Linux on even yet another. You can change
operating systems on one partition without affecting another.

Oh well...