/dev/sda and /dev/hda

Rick Stevens rstevens at internap.com
Tue Oct 23 23:27:00 UTC 2007


On Tue, 2007-10-23 at 17:13 -0600, Karl Larsen wrote:
>     As I have been working with 2 hard drives I have discovered for 
> certain that both hard drives change to /dev/sda when a partition on 
> them is booted. It happens that one is found at /dev/sdf and the other 
> is found at /dev/sdb. This leads to confusion and in my case I am not 
> sure what to think.
> 
>     Is this changing the disk drives a feature or is it a bug? If not a 
> feature I will write a bug soon.
> 
>     I understand the /dev/hda stays the first hard drive.

Well, sorta.  Depends on the kernel you're booting.  On earlier kernels
(pre-F7), IDE drives remained /dev/hdX.  Under F7 and later kernels,
ALL block storage is treated as SCSI (/dev/sdX) regardless of how it's
physically connected.  There's no differentiation at that level (there
is in sysfs, but let's not go there right now).

If you have other devices that were treated as SCSI before (USB, SATA,
whatever), your IDE stuff now gets added to the mix and the names can
change.  You also have to remember that grub uses a TOTALLY DIFFERENT
drive naming convention than a Linux kernel does.

Also note that in the Linux kernels, /dev/sdX refers to the ENTIRE
drive--not a partition on the drive.  /dev/sda is the first SCSI
disk (the ENTIRE disk), /dev/sda2 is the second partition on the first
SCSI disk.

----------------------------------------------------------------------
- Rick Stevens, Principal Engineer             rstevens at internap.com -
- CDN Systems, Internap, Inc.                http://www.internap.com -
-                                                                    -
-     If one is what one eats, then I am fast, cheap and greasy!     -
----------------------------------------------------------------------




More information about the fedora-list mailing list