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In Windows; you have the C:\ drive. This is the primary drive upon which Windows is installed.

However, Linux uses a different naming scheme: sda, sdb[1-4], etc. Can anyone give me a brief outline of it so I might actually understand it instead of being confused by it?

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It's worth noting that in normal use you don't need to use the /dev/sd* names. The equivalent of your C: drive is / (aka the root directory). You can see all drives by going to 'Computer' in the file manager. – Thomas K Aug 18 '11 at 9:47
Also note, MS Windows has been trying to discard the notion of drive letters for 8 (?) years now. For Linux (and Ubuntu), I for one do not miss them. – david6 Nov 21 '11 at 21:49

5 Answers 5

up vote 25 down vote accepted

In general, the letters (fd, sd, hd) refer to the device type ('SATA, SCSI/SATA, IDE'), the third letter is for the device order (a the first, b the second, etc) and the numbers refer to the partitions the device has, starting by zero.

  • hd refers to an IDE-type drive
  • sd refers to a SCSI drive in general, but is mostly popular for SATA drives and CD/DVD
  • fd is floppy disk

So for example:

  • the first (1) partition on your first (a) SATA drive is /dev/sda1
  • The third (3) partition on your second (b) SATA drive is /dev/sdb3
  • the second partition (2) of the second (b) IDE hard disk is '/dev/hdb2'

This device naming is more of a background one, as the actual point to access it a directory mount point.

I think that the following three articles will help you a bit:

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additionally, most modern distros allow referencing drives by uuid (a unique identifier for drives and other storage devices) if the kernel supports it there will be symlinks in /dev/disk/by-uuid/ that point to the "standard" /dev/sd** device nodes. This gives the benefit of having a stable reference to a drive even if you shuffle drives around on the system. – crasic Aug 15 '11 at 21:07

Just for clarity, on the Windows side you're confusing the file system naming with the drive naming. Windows hides the drive naming from you almost completely, but you can see examples in the registry and if you edit your boot.ini file. A disk reference there might look like this:


You can also see individual disks in the disk manager tool. The reason I bring this up is that the ntfs file system allows you to play all kinds of games. You can mount a separate disk to a folder in your C: and another drive at the same time, and unmounted disks may not have a drive letter at all. So don't confuse the file system from disk naming.

Linux is similar, here. sda1 is a common partition name, but it could be mounted anywhere on the file system.

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Pavlos G. is mostly correct, however /dev/hd** is no longer in use by IDE harddisks (and CD drives), they have been using /dev/sd** since kernel 2.6.19 (and ubuntu since 7.10, ~2007)

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You really shouldn't rely on the sd* naming scheme. It can change dramatically depending on drive spin up, hot plugging, and additional storage adapters. Best thing to use to uniquely address your device is the persistent links like /dev/disk/by-id/. Linux doesn't have the "boot from first disk" limitations and can also mount drives by label so drive ordering is really irrelevant.

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While SCSI and SATA will continue to be around for some time in mainstream desktop and laptop configurations, mobile devices using eMMC storage in the /dev/mmcblk*p* naming scheme have been around a few years and non-SATA high performance NVMe SSDs (/dev/nvme*n*) are not far away.

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This is would be better as an edit to the accepted answer. – muru Feb 15 at 16:31
@muru I voted for all the (currently) non-zero answers, I could have easily left that comment on each of them. – LiveWireBT Feb 15 at 16:38

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