Question on Partitioning Hard drive

[William Roberts;]

In <18805.27979475 at windy.dsir.govt.nz> sramtrc at windy.dsir.govt.nz writes:

>My personal preference is to have separate root and usr partitions. The
>root partition is not written to very frequently and so you can fill it
>right up to, say, 99% full instead of 90%. That way you get an extra 9%
>disk space. 
Don't forget to leave room for autoconfiguration (i.e. about 1.5 megabytes if 
you have a separate tmp partition, twice that if you don't). Various things go 
very horribly wrong if your autoconfiguration fails and fills up what little 
space there is left in root: in particular root is the default SWAPDEV so 
spare blocks in root have to be available if you want pipes & 
command-redirection to work. The /etc/startup.d/ae6 file is not at all 
resilient to pipe failures!

>I used to recommend a seperate /tmp partition but that was
>in the old days of the svfs filesystem which used to keep inodes separate
>from files. The ufs filesystem does not have this problem since it spreads
>the inodes out over the disk. 

We have separate tmp partitions: partly habit but also so that we don't worry 
about the fact that root is full for normal users (who therefore can't make 
pipes: see above).

>Another possibility that I have not tried
>since it involves a lot of work is to mount the root partition read-only.
>That gives a margin of safety and means that you only have to do one 
>backup since nothing changes.

It won't work. This is a nice trick (Sun have done things to achieve this) but 
A/UX gets most of the advantages by doing an fsck BEFORE A/UX get launched 
(unless you turned that off as well as autorecovery).
--

William Roberts                 ARPA: liam at cs.qmw.ac.uk
Queen Mary & Westfield College  UUCP: liam at qmw-cs.UUCP
Mile End Road                   AppleLink: UK0087
LONDON, E1 4NS, UK              Tel:  071-975 5250 (Fax: 081-980 6533)