partitioning scheme

[Steve Phillips]

Mad Unix wrote:
> what about /usr ?

Did you not read what I said about it ?

 > /usr  ------> SAN
 >
 > this is a _really bad_ idea.
 >
 > A lot of the time, you can get yourself in trouble if you are not
 > exceptionally careful about what is called at boot, and these days a lot
 > of stuff sits off /usr and you could accidentally isolate something that
 > needs to be run to allow - say, the SAN to come online.
 >
 > Back in the day, people used to partition stuff lots simply because
 > there was no such thing as a large hard drive (ok, this is not 100%
 > correct, but pretty close) - a lot of people claimed it was for data
 > retention incase of a system/drive crash, but seriously, how many people
 > that claim this do you know that have HAD a headcrash on a drive and
 > then tried to reconstruct data from the other segments of the drive -
 > generally when a drive crashes it will take out pretty much all the of
 > device rendering it ALL unusable. (and again, yes, at times you DO try
 > to reconstruct the data but it is NOT a common event and you can cause
 > more problems than you solve with this file system fragmentation that
 > everyone seems dead keen on)
 >
 > Your best protection is NOT more partitions it is things like RAID (i'd
 > mirror those two local disks) and good backups with a _tested_ restore
 > process.

Partitioning "because you can" is quite frankly, braindead. In the past 
there were very valid reasons for mounting lots of partitions all over 
the place, hard disk drives after all, were measured in 10's of _megs_ 
in size, not in gigs. These days not so much.

If someone can come up with a valid reason to partition to the nth 
degree, then sure - but until then - why bother ?

The biggest example I can give is not that relevant to many OS's due to 
the modernisation of things, but the principle remains the same.

<wee story>
In Solaris 7 there was no bash shell, so a classic thing to do was to 
download and install bash from sunfreeware. This always installed to 
/usr/local/bin - and was quite happily the default shell for a lot of users.

Someday, Mr Admin decided that the root /sbin/sh shell was a little 
plain, and with solaris, it will quite happily run with roots shell set 
to /usr/bin/bash

until of course you setup /usr as a separate partition and reboot and 
then nothing mounts as we cannot find the initial shell to mount /usr 
and the system becomes quite nastily broken and can take many hours to fix.
<end story>

Now, if we take this principle further, while a base install today will 
have no problem running with /usr as a separate partition, is there 
anything to gain from this ? (keep in mind, we only ever do things for a 
reason, not just 'coz that's the way its done')

Arguments for no /usr
a) the system will run quite happily without a /usr on a seperate partition

Arguments against a /usr partition
a) you can at times accidentally render the system unusable (you rely on 
the fact that everything needed to start the system resides on / and 
nothing in /usr)

The 'no /usr partition' argument seems to win out in my mind.

If you (or anyone else) has some form of logic as to why a /usr 
partition is a good thing then I'm all ears.

-- 
Steve
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