[comp.unix.ultrix] Dumping multiple partitions to a single tape.

map@cscosl.ncsu.edu (Mark Parris) (02/20/90)

Hardware & Software: 	Ultrix 3.0 	MicroVaxII

Background:
We currently do remote dumps across the network using the rdump command 
to backup our system.  This works fine, but it seems to be wasting a lot
of tape.  We're using 6250cpi tapes and dumping one filesystem/tape.
There's usually about 75% of the tape left unused after each dump. 

MY QUESTION: 
Is there anyway to get dump to dump multiple filesystems to a single tape?
Of course we would want standard recovery to work.  I've heard some kind
rumor of an undocumented switch on dump that allows one to do this but
that's all of the info I have.   

Please e-mail.  I will summarize.

*****************************************************************************
--Explanations, suggestions, clarifying comments, and constructive criticism 
	welcome and encouraged.  /-------------------------------------------
--Flames ignored.  |-----------/   Mark Parris  map@cscosl.ncsu.edu

map@cscosl.ncsu.edu (Mark Parris) (02/21/90)

First of all, thanks to all of those who replied to my question.  It's nice
to be able to post a question and receive 9 (so far) answers which are in
agreement, try them, and be able to summarize within 24 hours.   Thanks.

For the summary:

The key to dumping multiple filesystems to a single tape is to use the
no rewind tape device instead of the rewind one.  In my case, this meant
using /dev/nrmt8 instead of /dev/rmt8.  That's the only thing that had
to be changed regarding dumping.  I was able to dump 3 filesystems and
restore from each using this method.  

To restore dumps of this type, use the s switch on restore (or rrestore as
in my case.)  This option allows you to specify which dump image to restore
from.   If I had dumped /usr, /usr/var, and /local to the tape in that order
and I wanted to restore from local I would use s with an argument of 3 to
specify the image of /local.

The main thing to look out for is a filesystem that spans multiple tapes.  Such
filesystems should have tapes for themselves, or at least that seemed to be
the consensus.  I have no filesystems big enough to try it out.  Be sure you
have enough room left on the tape for the next filesystem.  (The S option
on dump is handy for this.)

Someone mentioned using mt rewind to rewind the tape after all of the
dumps were made.  I was unable to test this because there seemed to be no
equivalent for remote dumps.   I simply rewound using the tape drive rewind
button.

Thanks to all who replied.

*****************************************************************************
--Explanations, suggestions, clarifying comments, and constructive criticism 
	welcome and encouraged.  /-------------------------------------------
--Flames ignored.  |-----------/   Mark Parris  map@cscosl.ncsu.edu

davew@gvgpsa.GVG.TEK.COM (David C. White) (02/22/90)

In article <1990Feb21.051622.10343@ncsuvx.ncsu.edu> map@cscosl.ncsu.edu (Mark Parris) writes:
    
[deleted text about using the nrmt device]
    
>Someone mentioned using mt rewind to rewind the tape after all of the
>dumps were made.  I was unable to test this because there seemed to be no
>equivalent for remote dumps.   I simply rewound using the tape drive rewind
>button.

There is an easy workaround for this one.  For your last dump use
the rewind device and the tape will rewind automatically when
the dump is complete.
-- 
Dave White	Grass Valley Group, Inc.   VOICE: +1 916.478.3052
P.O. Box 1114  	Grass Valley, CA  95945    FAX: +1 916.478.3887
Internet: davew@gvgpsa.gvg.tek.com     UUCP:  ...!tektronix!gvgpsa!davew

khaw@parcplace.com (Mike Khaw) (02/24/90)

davew@gvgpsa.GVG.TEK.COM (David C. White) writes:


+In article <1990Feb21.051622.10343@ncsuvx.ncsu.edu> map@cscosl.ncsu.edu (Mark Parris) writes:
+    
+[deleted text about using the nrmt device]
+    
+>Someone mentioned using mt rewind to rewind the tape after all of the
+>dumps were made.  I was unable to test this because there seemed to be no
+>equivalent for remote dumps.   I simply rewound using the tape drive rewind
+>button.

+There is an easy workaround for this one.  For your last dump use
+the rewind device and the tape will rewind automatically when
+the dump is complete.

If dump behaves like tar, then this will cause the tape to rewind to
BOT *before* dumping the last filesystem, thus destroying your earlier
dump(s).
-- 
Mike Khaw
ParcPlace Systems, Inc., 1550 Plymouth St., Mountain View, CA 94043
Domain=khaw@parcplace.com, UUCP=...!{uunet,sun,decwrl}!parcplace!khaw

wyatt@cfa.HARVARD.EDU (Bill Wyatt) (02/26/90)

|> There is an easy workaround for this one.  For your last dump use
|> the rewind device and the tape will rewind automatically when
|> the dump is complete.

> If dump behaves like tar, then this will cause the tape to rewind to
> BOT *before* dumping the last filesystem, thus destroying your earlier
> dump(s).

WHAT??? If your tar does this, it's broken, broken, BROKEN!


Bill Wyatt, Smithsonian Astrophysical Observatory  (Cambridge, MA, USA)
    UUCP :  {husc6,cmcl2,mit-eddie}!harvard!cfa!wyatt
 Internet:   wyatt@cfa.harvard.edu
     SPAN:   cfa::wyatt                 BITNET: wyatt@cfa

davew@gvgpsa.GVG.TEK.COM (David C. White) (02/27/90)

In article <671@parcplace.com> khaw@parcplace.com (Mike Khaw) writes:
>+In article <1990Feb21.051622.10343@ncsuvx.ncsu.edu> map@cscosl.ncsu.edu (Mark Parris) writes:
>+There is an easy workaround for this one.  For your last dump use
>+the rewind device and the tape will rewind automatically when
>+the dump is complete.
>
>If dump behaves like tar, then this will cause the tape to rewind to
>BOT *before* dumping the last filesystem, thus destroying your earlier
>dump(s).

Haven't really tried it with tar,  but it works as it should with
dump.  The tape should not rewind until after the current operation.
You want to the the norewind device for all but the last dump.  From
mtio(4):

     The special files ``rmt0l, ..., rmt31l'' are low density,
     ``rmt0m, ..., rmt31m'' are medium density (when a drive is
     ``triple density''), and ``rmt0h, ..., rmt31h'' are high
     density. All these special files cause a loaded and on-line
     tape to automatically rewind to the beginning-of-tape (BOT)
     when closed.
     ^^^^^^^^^^^
-- 
Dave White	Grass Valley Group, Inc.   VOICE: +1 916.478.3052
P.O. Box 1114  	Grass Valley, CA  95945    FAX: +1 916.478.3887
Internet: davew@gvgpsa.gvg.tek.com     UUCP:  ...!tektronix!gvgpsa!davew