Jul 302018
 

Alternatively, why does Windows use drive letters? Because if you are coming from an old unix background, drive letters are just as weird as the lack of them if you are coming from a Windows background.

I mean, why is Windows installed on drive C? What ever happened to drives A and B?

Technically Linux does have the equivalent of drive letters but they are rarely used directly (unless you’re weird like I am). For example I currently have an SD card plugged into my desktop system, and it has the path /dev/disk/by-label/EOS_DIGITAL (or /dev/sdo1).

Historically, Unix (which is loosely the predecessor of Linux) ran on large minicomputers where system administrators would decide what disks were “mounted” where.  The Linux equivalent of drive C is effectively “/” (root), and you can attach (or “mount”) disks at any point underneath that – for example /home.

This allowed people to use an old Unix machine without worrying where this disks were; and allowed system administrators to add and remove disks as and where they were needed. These days we are all system administrators as well as users – that little voice you hear from time to time saying things like “When would be a good time to update the operating system?” and “I must clean up those temporary files all over the place” are your inner system administrator speaking up.

And if you don’t hear that inner voice, cultivate it!

With device paths, Linux has the opportunity to create sensible friendly names for disks, but a historical accident has resulted in almost every kind of disk being identified as a SCSI disk – SATA disks (a normal hard disk), SAS disks (server hard disks), Fiber Channel disks (SAN hard disks), and even USB storage devices all use SCSI commands.

So nearly all Linux disks are identified as /dev/sd followed by a letter (a “drive letter” – we can’t get away from them) and a number indicating the partition. Fortunately there is also the relatively new /dev/disks directory that has slightly friendlier names for disk devices. If you are getting into low-level disk management, learn these directories; in particular if you are looking into enterprise disk management look at WWNs (each disk has a unique “world-wide-number”).

Now back to Windows. Windows is the descendent of DOS, which goes back to the time when PCs may not have had hard disks and by default would have booted off a floppy disk in drive A with a data disk in drive B. Later PCs came with hard disks which used drive C on the assumption that you would have one or two floppy drives.

Windows has been updated over the years and there is a great deal of sophistication under the surface, but it does act a bit conservatively when it comes to drive letters – A and B are by default reserved for floppy drives even though I haven’t seen one of those on an ordinary system for years. You can use A and B for other purposes such as mapping network drives – A makes a good drive for a NAS drive.

If we get away from the terminology of “drive letters” and “device paths” and instead refer to them as “storage device names”, both Linux and Windows have “storage device names” but Linux prefers to hide that level of detail.

Personally I prefer the Linux way, but whatever floats your boat.