[mdlug] Reordeing IDE drives in a system

[Paul]

"Clinton V. Weiss" <cvweiss at gmail.com>, on Mon Oct 01, 2007 [05:11:46 PM] said:
> Ubuntu's fstab references the drives based on their serial number -
> not sure how.  This could be quite useful tho since the drives could
> be re-arranged at anytime without affecting the system (while the
> system is off of course).
> 
> Might be some good food for thought on getting it done that way.
> 
> -- 
> Clinton V. Weiss
> cvweiss at gmail.com

	Hi;

	You can mount a filesystem based upon the device node, or
either of the filesystem's label or UUID. (not the drives serial
number) The fstab man page describes the format for the first
field in the /etc/fstab file to do this with filesystems that
support a label or UUID.
	This later option solves the problem of re-ordered drives,
but with PATA drives you will need to make sure that they are
jumpered properly so they are all detected and dont step on each
other. Also, because two drives on the same controler channel
will have performance problems when doing a lot of I/O between
each other, ordering of PATA drives is usually a worthwhile
strategic endeavor. For example, having your main drive on hda
and your burner on hdb could cause problems during burning.
	PATA drives can have upto four jumpered settings: Master alone,
Slave, Master with Slave, and cable select. (Some dont distinquish
between Master+Slave and Master alone, some do) A Master disk
connected to the first controller channel will be /dev/hda, the Slave
on that channel will be /dev/hdb (and so on), regardless of what
connector on the ribbon cable you connect them to. If you have
a proper cable, you can just jumper the drive 'cable select', and
it should decide for itself whether it is Master or Slave depending
on which connector on the ribbon cable it gets.
	Drives are sometimes weird, either in combination with other
drives or controlers, so sometimes it is best to just specificly
set the jumpers to assign them their roles. I haven't seen a drive
in aeons that didnt have the jumper settings printed on it.

Paul
set at pobox.com