Path: utzoo!mnetor!uunet!husc6!purdue!umd5!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.wizards
Subject: Re: A few questions about 4.3BSD partitions and cylinders
Message-ID: <10286@mimsy.UUCP>
Date: 21 Jan 88 18:08:38 GMT
References: <11271@brl-adm.ARPA> <13380@oliveb.olivetti.com>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 32

[Why are all roots the same size (15884 sectors)]
>In article <11271@brl-adm.ARPA> rbj@icst-cmr.arpa (Root Boy Jim) writes:
>>For hysterical raisins. I think they come from the gee I'm a tree of
>>the RP06. It just seemed convenient for all root file systems to be
>>the same size, so they can be dd'ed easily.

In article <13380@oliveb.olivetti.com> jerry@oliveb.olivetti.com
(Jerry Aguirre) writes:
>Except they arn't.  [The geometry is different which makes mkfs
>use different amounts out of those 15884 sectors.]

>Of course if you dd then it doesn't matter bacause you won't be paying
>any attention to cylinder boundries.

Right.

Moreover, the next release has disk labels, stored on sector zero
of each pack.  If you `dd if=/dev/rp06-root of=/dev/rm05-root' you
will relabel your RM05 as an RP06.

*Root file systems should be copied with dd ONLY if the two drives
are identical and (now) partitioned identically.*

>Meanwhile I waste over half a meg of my root file system as either
>hidden or unusable.

I ignore the sizes in the distributions and make up my own.  On
everything except one Microvax, I have 30+ MB roots.  No more
running out of space for the next vmunix. . . . :-)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris