Xref: utzoo comp.unix.questions:16155 comp.unix.ultrix:1654
Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!tank!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.questions,comp.unix.ultrix
Subject: Re: Preen with NFS?
Keywords: preen, Ultrix, NFS, fsck
Message-ID: <19408@mimsy.UUCP>
Date: 5 Sep 89 12:40:03 GMT
References: <66554@linus.UUCP> <7817@cbmvax.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 35

>In article <66554@linus.UUCP> dsg@mbunix.mitre.org (Goldberg) writes:
>>We are planning to upgrade our 8600 from Ultrix 2.3 to 3.1 in the very
>>near future.  Since version 1.2 we have been using Chris Torek's preen
>>program to make fsck's run faster.

Actually, Fred Blonder wrote the original version of preen.  I simply
rewrote it and cleaned it up.

In article <7817@cbmvax.UUCP> grr@cbmvax.UUCP (George Robbins) writes:
>I'm not familiar with this preen program, but I would point out that DEC has
>improved the "fsck -p" option so that it doesn't bother with filesystems
>that are "clean" or haven't been modified since last unmounted.

This is certainly useful, but is a very different thing.

What preen does is run `fsck -p' on all disk drives in parallel.  `But
wait', I hear, `fsck -p already runs in parallel via the pass numbers.'
Nope.  fsck -p *oozes* in parllel via the pass numbers, unless all your
disk partitions take exactly as long to check as all others that have
the same pass number.  If you have more than one file system per drive,
this is almost guaranteed to be false.

Preen depends on the disk naming scheme, and assumes that two
partitions are on the same physical drive if and only if the device
names match except for the partition letter.  Thus, /dev/ra0[a-h] are
all `the same', but all differ from /dev/ra1[a-h], etc.  Except on
Encore UMAX systems, I have never seen this assumption violated (and on
ours, we un-violated it because we found `/dev/usr' just plain
annoying).  In any case, preen will be unnecessary in 4.4BSD, where
fsck has been modified to use preen's scheduling algorithm instead of
the old pass numbers.  If Encore intend to keep up with 4.4BSD, they
may have to change their naming scheme back....
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris