tape listing

[Rick Stevens]

ajay wrote:
>  
> 
> 
> On Sat, 16 Jul 2005 gerrynix wrote :
>  >
>  > > > hi gurus
>  > > >
>  > > > i try to list my tape hp 40gb (under compression)
>  > > >
>  > > > ------------------------------------------------------
>  > > > [root at tivimtech ajay]# tar vft /dev/st0
>  > > > tar: This does not look like a tar archive
>  > > > tar: Skipping to next header
>  > > > tar: Archive contains obsolescent base-64 headers
>  > > >
>  > > > -------------------------------------------------------
>  > > >
>  > > > it do not list anything and gives this error and comes out.
>  > > > is there any way i can mount it, if yes what is mount type ?
>  > > >
>  > > > i use this command to backup:
>  > > > i am very sure it does backup as i checked date against backup.log
>  > > > it changes everyday and shows latest date time as supposed.
>  > > >
>  > > > # Daily Backup on the Dat
>  > > > tar cvfz /dev/st0 /home /data /etc /var/spool/mail /var/www
>  > > >  >/var/log/backup.log &
>  > > >
>  > > > It is scheduled in cron.
>  > > >
>  > > > here is some part of this log.....
>  > > >
>  > > > UW PICO(tm) 4.2                    File: /var/log/backup.log
>  > > >
>  > > >
>  > > > home/
>  > > > home/niteen/
>  > > > home/niteen/.bash_history
>  > > > home/niteen/.addressbook
>  > > > home/niteen/.addressbook.lu
>  > > > home/niteen/.bash_logout
>  > > > home/niteen/.bash_profile
>  > > > home/niteen/.bashrc
>  > > > home/niteen/.canna
>  > > > home/niteen/.emacs
>  > > > home/niteen/.esd_auth
>  > > > home/niteen/.fetchmailrc
>  > > > home/niteen/.fonts.cache-1
>  > > > home/niteen/.gtkrc
>  > > > home/niteen/.gtkrc-1.2-gnome2
>  > > > home/niteen/.ICEauthority
>  > > > home/niteen/.mailboxlist
>  > > > home/niteen/.pinerc
>  > > > home/niteen/.recently-used
>  > > > home/niteen/.rhn-applet.conf
>  > > > home/niteen/.viminfo
>  > > >
>  > > > ..............................
>  > > >
>  > > > I am confussed why it says "This does not look like a tar archive" ??
>  > > >
>  > > >
>  > > > help me from this dilemma !!!
>  > >
>  > > Did you rewind the tape before trying to list its contents?
>  > >
>  > >      # mt -f /dev/st0 rewind
>  > >      # tar tvf /dev/st0
>  >
>  >
>  >Looking at your command . . . You have used the "z" option to
>  >gzip your backup. Man page says to also use the z option to
>  >to view/extract . . . Try:
>  >
>  >        # tar tzvf /dev/st0
>  >
> 
> 
> thanks a lot it "tar tzvf /dev/st0" solved my problem.
> Actually i was missing "z" as i have compressed archive.
> 
> thanks.
> 
> i have one or more query :
> 
> 1.  How can i check how much tape has been written and how much is free?

That's very difficult to do using things such as "tar", as it doesn't
necessarily know how big your tape is, nor what the compression ratio
is (hardware/software, etc.).

> 2.  Once i know free space of tape, how can i access how much data i can 
> add more?

You'd need to move past the end of data filemark of the current tape to
append things to it and you'd need to use the non-rewind version of the
drive (/dev/nst0).  The commands would be:

	# mt -f /dev/nst0 rewind
	# mt -f /dev/nst0 eod
	# tar cvzf /dev/nst0 data
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- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-      Cuteness can be overcome through sufficient bastardry         -
-                                         --Mark 'Kamikaze' Hughes   -
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