history of homedirs on unices

[Scott Stevens]

On Sat, 24 Sep 2005 08:55:28 -0400
shoppa_classiccmp at trailing-edge.com (Tim Shoppa) wrote:

> > Minix however used to have its homedirectories in /usr.  Did "real"
> > unices used to have the homedirectories their as well?
> 
> This is actually a matter mostly of partitioning.  On a system with
> a small number of spindles, "/usr" was usually the largest
disk/partition,
> and most users had their home directories there (this tradition
continues
> with many commercial Unices).
> 
> On a system with a large number of users and spindles, very often
> there were multiple root directories used for home directories.  For
> example there would be a disk mounted as /users1 and it would
> have user's home directories of /users1/aaron and /users1/able and
> /users1/acton etc., and then there would be a disk mounted as /users2
> and it would have a bunch of home directories on it, etc.
> 
> Other places would mount these as /usr/users1/aaron, /usr/users1/able,
> etc., keeping up the tradition of having them under the "/usr"
umbrella.
> 
> Sometimes all the disparate spindles were hidden by making links
> from a common /usr/users or /users directory to the spindle/directory
> where the home directory really resided.  This is much nicer if you're
> gonna be migrating to larger disks someday.
> 
> Many of the inconvenient things of spindles and mount points we no
> longer do if not necessary.  I suppose /home is a good point to start
> at and then if necessary use link to the actually partition where the
> user's home directory resides.
> 
> For some reason, the old way of partitioning unix systems still lives
> on although the need for multiple mount points and spindles doesn't
> matter much in a world of multi-hundred-Gbyte disks.  I suppose
> it's like "always make your swap partition twice the size of physical
> memory" even though the rationale behind that recommendation was
> stale 15 years ago and is much more stale today!
> 

It is actually a reliability/security mechanism to split the system's
filesystems over multiple partitions.  If you put the user-writable
directories in the same spot as critical system things, a runaway
user-level process (or just a drive space hog user) that fills the drive
is less likely to crash the system by using up space the system needs.