Windows uses letters to represent physical drives on your machine, making it a lot easier to understand what's happening where.
The problem with Windows' method of labeling the physical volumes and their respective partitions is that if you dual-boot, most of the time overlaps will occur. Right now it is all too likely that if you dual-boot you have different partition labels "facing" each operating system that don't seem to add up. To clarify (just an example):
Windows XP (installed on the first partition of the first drive) sees:
1. C:\ for the XP partition
2. D:\ for the Vista partition
3. E:\ for a common data partition shared between the two
Windows Vista (sitting on the first partition of the second drive) sees:
1. C:\ for the Vista partition
2. D:\ for the XP partition
3. E:\ for the data partition
So what's the right way to use drive letters in EasyBCD? It's quite simple, actually: Always use the drive letters that operating system you are currently booted into sees!
EasyBCD "translates" the letters that current OS sees into numbers for the drive and partition. So if you're in XP and EasyBCD asks for the Vista drive, tell it
D:, because that's what XP thinks it is. Nevermind what Vista believes, it's the operating system you are currently in that matters.
Different operating systems number their drives and partitions in different ways. The debate on the "right" way to do this is as old as time itself, and goes back to whether you consider "0" or "1" to be the "first number" in any index-based sequence.
The Linux Camp did it logically... For the most part. When you are dealing with Linux hard drive and partition numbers, start counting both from the number zero. For example,
(hd0,1) is the second partition of the first hard drive. Pretty easy to follow, just
(hdd,p) where the second 'd' is the drive number and the 'p' is the partition number.
But when you're within Linux dealing with the drives and devices, you'll be shocked (and rightly so) to realize that they've done away with this straight-forward numbering scheme and opted to use a combination of both letters and numbers... and categories too!
The different kind of "numbers" you will encounter in the Linux world:
In the list above "L" is a small-case letter, and "#" is a number. hd(#,#) has already been discussed, and is primarily used before booting into Linux, in programs like Lilo and GRUB.
hdL# and sdL# are a bit more confusing. The "h" and "s" differentiate between IDE/ATA drives and SATA/SCSI drives respectively. Even more confusing, at this point numbering starts from one again! So the third partition of the second IDE drive on your PC is
hdb3 while the second partition of the first SCSI drive on your machine is
sda2. Confused yet?
It gets worse. Linux doesn't actually understand
sda1 as referring to a drive – it's just a combination of letters and numbers to it. To make Linux understand what you want, you have to prefix the letter & number combination with
/dev/. So if you're in the console and you want to tell Linux to access the 2nd partition of the 3rd SCSI drive, you would have to actually write
Ironically, in an attempt to make things a bit "easier," certain Linux distributions (mostly just Ubuntu) now use sdL# notation for everything. Basically they've "merged" the two hdL# and sdL# lists into one, which does make it easier in a way… except of course that you don't know whether it's IDE or SATA drives that get listed first!
Microsoft may have picked a more unusual method of "counting" the drives and partitions, but at least they stuck to it the whole way through. Despite its weirdness, it's quite easy once you get what's going on:
On Windows (and therefore, in EasyBCD as well… for the most part), drives start counting at 0, but partitions start from 1! So drive 0, partition 2 is the second partition of the first hard drive. Drive 3 partition 1 is the first partition of the fourth drive, and so on and so forth.
This may seem a bit off at first, but there's a good reason for this. In Windows, you can access the MBR (something EasyBCD does quite often) of each drive by setting the partition equal to zero. So drive 0 partition 0 is actually the MBR of the first hard drive. However, when dealing with EasyBCD and most other Windows programs, you will never reference the MBR, so just remember that drives start from 0 and partitions from 1. Even in boot.ini.