Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wasatch!cs.utexas.edu!uunet!mcvax!ukc!dcl-cs!aber-cs!pcg
From: pcg@aber-cs.UUCP (Piercarlo Grandi)
Newsgroups: comp.unix.microport
Subject: Re: ps *insists* on accessing floppy on Microport SysV/AT 2.4
Summary: indeed /dev/swap is /dev/dsk/0s25... just change it.
Keywords: ps, /dev/swap, "is it safe?"
Message-ID: <903@aber-cs.UUCP>
Date: 2 May 89 22:21:28 GMT
Reply-To: pcg@cs.aber.ac.uk (Piercarlo Grandi)
Distribution: eunet,world
Organization: Dept of CS, UCW Aberystwyth
	(Disclaimer: my statements are purely personal)
Lines: 58

In article <291@tree.UUCP> stever@tree.UUCP (Steve Rudek) writes:

    About a month ago I wrote describing how I'd managed to save the root
    file system by using "installit" and substituting "list" (a new
    installation) for list.ug (upgrade path).  It worked except that "ps"
    thereafter insisted on always accessing the floppy drive.
    
    I got a number of thoughtful responses (thanks!) with with the most
    practical being:
    
    >From: pcg@aber-cs.UUCP (Piercarlo Grandi)
	[ ..... ]
    I tried "ps -s /dev/null" and it does NOT try and read the floppy.  I don't
    "know why" though.  I gather I'm running the kernel still somehow rooted on
    the floppy (even though it isn't).

Well, the kernel is probably rooted on the hard disc. Who knows where your
swap partitions is... Have you run hdrt.ptch? You probably want your swap
partition to be /dev/dsk/0s1, so do "patch /system5 swapdev 1", if not
already done. Or, better still, and very recommended, take the link kit and
regenerate the kernel from scratch. NOTE: you had better check with divvy
that indeed /dev/ds/0s1 is set up as a swap partition.

    Based on the following "ls -la"s is it safe to say tht the two devices
    are NOT linked?  (It appears that swap is linked instead to
    /dev/dsk/0s25...yes?)
  
    brw-r--r--   1 root     sys        1,198 Mar 23  1986 /dev/swap
    brw-r--r--   5 root     sys        1, 70 Mar 28 17:21 /dev/dsk/fd
    brw-r--r--   1 root     sys        1,198 Mar 23  1986 /dev/dsk/0s25

The two devices are not linked, but 1,198 is the same as 0s25, which is the
same as fd, except that the first track is skipped. In other words,
/dev/swap still denotes the floppy.  ps(1) reads /dev/swap to get the status
of non core resident processes, and if this is a floppy device, you get into
trouble.

    Is it "safe" to just "ln /dev/swap /dev/dsk/fd" ??  I like to have a
    little bit of assurance that I'm not going to regret my actions before I
    do unfamiliar things as root;

Don't! do instead "ln /dev/dsk/0s1 /dev/swap", to make swap a synonym of 0s1,
the hard disk swap partition, (not fd a synonym of swap, which is the same
device as fd). You phrase "unfamiliar things with root" make me wish that
you read some papers on Unix internals; the two papers on Unix internals in
the V7/BSD docs by Thompson and Ritchie are still the best and mostly
current (well, until 5.2 -- 5.3 has completely different memory mgt.).

   I *don't* have a tape backup unit (speaking of which, can anyone
    recommend an adequate unit which they *know* works under 2.4?).

Any good QIC-02/QIC-36 controller based unit. Wangtek, Everex and Archive
(probably the cheapest).  You really want the 60MB 1/4" QIC-24 version, not
any other (I don't like the higher capacity ones, 125/150MB).
-- 
Piercarlo "Peter" Grandi           | ARPA: pcg%cs.aber.ac.uk@nsfnet-relay.ac.uk
Dept of CS, UCW Aberystwyth        | UUCP: ...!mcvax!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk