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From: afc@shibaya.lonestar.org (Augustine Cano)
Newsgroups: unix-pc.general,comp.sys.att
Subject: Multiple partitions on 1 and 2 Unix PC hard disks.
Message-ID: <1990Nov16.033801.978@shibaya.lonestar.org>
Date: 16 Nov 90 03:38:01 GMT
Sender: afc@shibaya.lonestar.org (Augustine Cano)
Organization: Multidisciplinary Designs Unlimited
Lines: 82

In preparation for a 2 stage upgrade, I now seek some net advice.
The first stage of the upgrade is to install the large HD I just bought
(A priam 519, 1224 tracks, 15 heads, 190 Mb unformatted.)  I would do
everything at the same time, but John's HD2 board is not shipping yet.
I already have a WD2010 and the P.51 option installed.

My original plan is to make 2 partitions of equal size in this new disk:
/ and /u.  The pros and cons, as I see them are:

Pros: 1 - /u sees most of the disk activity, but being a separate
          partition, will not mess up /.  Since it can be dismounted, it
          can be unfragmented easily with packdisk.

      2 - / and /u will be large enough that they won't fill up immediately.

Cons: 1 - /usr/spool, which sees lots of disk activity, will temporarily
          be messing up the / partition.

      2 - activity in /tmp will also somehow fragment the root partition.

      3 - having / and /u on the same disk would make for lots of head
          movement.  However, would this be any worse than the standard,
          one-partition per drive, unix pc way of doing things?

      4 - /usr/lib/news, with all its updating of log files, history
          files and active file would fragment the root partition some.
          I suspect, though, that giving /usr/lib/news its own partition
          wouldn't be a good idea.

Later, when I get the HD2 board, I'll add the current drive (an ST-4096)
as drive 2.  This drive will also be partitioned in 2 equal chunks,
roughly 40 Mb each.  One will be /usr/spool and the other will remain
as a mostly empty space for backups, archives, or semi-permanent temporary
storage.

Another possibility is to have /tmp as the other partition on
the second drive.  This would speed things up, but somehow I feel that a
40 Mb /tmp is excessive.  How big should /tmp be, if it gets its own
partition?  I have stuffed some pretty big things in /tmp before and it was
nice to have all the free space on the drive available, so maybe the speed
penalty of having /tmp in the / partition is worth it.  Comments?

Also, I seem to recall that without re-linking the kernel, you
can only have 2 partitions per drive (in addition to /dev/fp000 and
/dev/fp001), is this correct?  Does this also apply to the second drive,
without a swap partition?  Also, would it do any good to have a swap
partition larger than 5000 blocks?  (I also plan to add 1.5 Mb RAM to a
RAM-less combo board.)

At this point the pros and cons, as I see them now are:

Pros: 1 - /usr/spool will now have its own partition on the slower drive,
          thus no longer fragmenting /.

      2 - there will be plenty of space (~75 Mb) in / for /usr/man,
          /usr/doc, /usr/src/, /usr/lbin, /usr/local and all the other
          standard directories that don't change very often.

      3 - if the 2nd drive quits, I can just dismount it, re-make
          /usr/spool in the root partition and I'm in business again.
          This is partially why I'd rather keep /u on the main drive
          (size and speed (22 vs 28 ms) are the main reasons).
          If the big drive quits, I'm in trouble :-)

Cons: 1 - like 2, 3 and 4 above, depending on where /tmp is put.
          But is there really a disadvantage to having 2 drives and lots
          of space? :-)

Opinions anyone?  Those of you who have 2 HDs and/or multiple partitions,
how did you do it?  Any other considerations I have overlooked?  Have any
benchmarks been run on different partitioning schemes and what directories
were placed where?  Will some programs be broken by the multiple partitions?
Which ones?

I'll post a summary of e-mail responses.  However, posting might be
appropriate, since at least the participants in the big HD group buy would
benefit.

Thanks.
-- 
Augustine Cano		INTERNET: afc@shibaya.lonestar.org
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