Why partition disks?

[Michael Meissner]

In article <157 at locke.water.ca.gov> rfinch at caldwr.water.ca.gov (Ralph
Finch) writes:

| We are about to receive two 1.2GB SCSI drives (Wren 7s) :-) :-) .
| These will be used mainly for data storage with some space for home
| directories and public domain stuff.  We are wondering how to
| partition these things when they get here.  Actually we would like 1
| partition per disk if it won't hurt anything.
| 
| 1)  Does partitioning affect performance (capacity and speed)?
| 
| 2)  Does partitioning affect fragmentation?  Does one have to worry
|     about fragmentation with Unix, or SCSI, or ?

There is some folklore that things placed in the middle of the disk
will be accessed quicker than things placed on either end since the
head is typically somewhere near the middle.  Thus some system
managers have placed absolutely critical partitions in the middle to
deal with this (yes, I've done this in a previous life).  I'm not sure
it's worth it, unless you have some fixed size data base that accounts
for 80% of your disk traffic (though of course it might be an ideal
spot for /usr and/or swap).

It is possible that fsck and/or the kernel on some UNIX ports can't
deal with a 1.2G disk (which is why the original unix partitioned
disks).  If your system limits you to 16-bit inodes, you probably
should partition the disk, since you are getting into the range that
the system won't be able to allocate all of the available disk blocks
(I forget where the cutoff value is).  Also, cpio can only deal with
16-bit in binary mode or ~18 bits in decimal inodes.

Fragmentation will always exist, but UNIX gives you no tools to deal
with it (other than full dump and load).
--
Michael Meissner	email: meissner at osf.org		phone: 617-621-8861
Open Software Foundation, 11 Cambridge Center, Cambridge, MA

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