[ubuntu-uk] killed box through /var :P

[Liam Proven]

2009/1/6 Neil Greenwood <neil.greenwood.lug at gmail.com>:
> 2009/1/6 Liam Proven <lproven at gmail.com>:

>> On DOS-based OSs, there is good reason to use only logicals on all but
>> the 1st drive, because it makes drive letter assignment by the OS.
>
> I guess you meant "stops drive letter assignment by the OS."?
> Otherwise you're missing something from that sentence :-)

Oops, sorry. I missed a phrase off.

What I meant to say is this:

On DOS-based OSs, there is good reason to use only logicals on all but
the 1st drive, because it makes drive letter assignment by the OS a
lot more logical.

To elaborate:

DOS assigns drive letters thus:

[1] iterate through all hard drives, assigning letters to visible
*primary* partitions in drive order
(some DOSes will give even partitions they can't read a letter)
[2] *then* go back to the first drive and iterate through disks
[3] for each drive, iterate through all (readable) logical drives *on
that drive*, assigning letters

This gets complex very fast.

Imagine 2 hard disks, each with 3 partitions.

If they both have 1 primary, 2 logicals:
disk 1 partition 1 = C
d2p1 = D
d1p2 = E
d1p3 = F
d2p2 = G
d2p3 = H

So C, E & F are on disk 1; D, G & H are on disk 2. Confusing, huh?

Now, if you do it the "formally correct" way, with just 1 primary on
the 1st drive, no primaries on any other drive(s), just one extended
partition per disk with logical drives:

2 drives, 3 partitions per drive, as before
d1: 1 primary, 2 logicals
d2: 3 logicals

Drive letter assignments:

d1p1 = C
d1p2 = D
d1p3 = E
d2p1 = F
d2p2 = G
d2p2 = H

So, disk 1 is C, D & E; disk 2 is F, G & H. Which is what one might
expect: first all the partitions on the 1st drive, then all the
partitions on the 2nd. Much cleaner, simpler and less confusing.

This is the letters you get with any version of DOS, Windows 1/2/3 or
95, 98 or ME. It's also how OS/2 works and NT 3 and 4. (Disclaimer:
I've only played with FreeDOS.)

With 2000 and XP, it's how letters are assigned, but you can reassign
anything but the boot drive.

With Vista and Windows 7, all bets are off.

It still applies if you have a dual-boot machine with Linux or some
other non-DOS OS. And before now, I've had machines with Win98, 2000,
XP and three or four Linux distros plus assorted data partitions on
three hard disks. My current main PC has DOS, XP, Vista, Ubuntu, SUSE
and Mint on it.

It gets very intricate, so following the "rules" is a good plan.

-- 
Liam Proven • Profile: http://www.linkedin.com/in/liamproven
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