using sysinstall upgrade as a repair solution

Kevin Kinsey kdk at
Tue Mar 6 20:02:08 UTC 2007

Jerry McAllister wrote:
> The long ago origins of making things in many partitions was when
> disks were much much smaller.  So were backup media.   It was common
> to have each piece on a separate disk.   Then disks got big enough
> to put more than one part on and so on.
> Now, there are a couple of good reasons to still divide a disk in to
> partitions.  One is mentioned, sort of, above.  You want to isolate
> areas that may grow unexpectedly from critical disk space.  So, /var
> which contains logs and database stuff and spools gets its own partition
> to keep it from over-filling root.   /tmp and user home directory space
> are also such disk areas whose growth might not be predictable.
> Another reason is for convenience with backups.   You may want to
> reduce the size of partitions that are being backed up, either to
> fit media or to be more convenient.  If only stuff in the partition
> with users' home directories changes, then you only have to make
> regular backups of that.  The other parts you only backup when you
> make a new install or whatever.  Some things like /tmp you don't bother
> to ever back up.    It also can be less to have to restore if one 
> partition goes belly up, though that is less true nowdays when the users' 
> space (not necessarily /usr - that is an old convention.  Now it is 
> common to use /home for users' home directories, since /usr really contains 
> installed software) may be by far the largest space on a system, depending 
> on how the system is used.  
> Another reason to break things up is to have to load the least amount
> possible when there are problems.   You have to have / to boot in to
> single user mode to work on things.  But you don't have to have the
> rest of the stuff.   The smaller you make root the less likely some
> disk problem will show up in the root partition, making it more likely
> you can get at least some of the system up to work on the problem.
> The fourth reason to have separate partitions is to make it easier
> to isolate things.   You may want to make a certain amount of space
> available for users to write in, but want to keep them out of other
> space.   There are various ways to do it.   Having things grouped
> conveniently in some defined area makes it a little easier.

What Jerry said ;-).  Thanks for expressing what I couldn't OTTOMH.

>> Incidentally, 150MB doesn't seem very large for a root partition IMHO. 
>> I've not read the handbook recently, but I generally use a gig for /.
> If you divide out /var and /usr and /tmp and /home, then 150 MB is
> plenty for root.   I am currently using about 120 MB on this machine
> which is due a good cleanup.  

I only partition /, /var/, and /usr/, so /tmp stays in the root slice; I 
make mention of this fact (150M being small) because of the 
previously-mentioned case in which installworld puked because / was full 
(this *was* with a separate /tmp) and there was nothing really there 
except default stuff (had been a DesktopBSD system, maybe someone with 
more experience there could comment).  The box was going from 5.3 under 
an (older) DesktopBSD test install to FBSD 6.2; I worked 'round the 
issue by moving /stand, but ended up re-installing 6.2 from CD to give a 
slightly more junior guy more experience with sysinstall (AAMOF I've 
made him do it on two boxen today, heh heh heh)....

Kevin Kinsey
Life is what happens to you while you're busy making other plans.
		-- John Lennon, Beautiful Boy

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