Re: tape command for solaris 8

From: Jason (greenbuffalocabbageman_at_yahoo.com)
Date: 08/22/03

  • Next message: Douglas O'Neal: "Re: remote access KVM switch" 
    Date: 22 Aug 2003 07:53:28 -0700

    ma7777772@hotmail.com (TingChong) wrote in message news:<451a2a55.0308180941.3f0f0326@posting.google.com>...
    > What are the answers to questions 1 to 4?
    > Thanks.
    >
    > js@cs.tu-berlin.de (Joerg Schilling) wrote in message news:<bhbkvm$h4l$1@news.cs.tu-berlin.de>...
    > > In article <news-E030E2.12303512082003@news.tdl.com>,
    > > Michael Vilain <vilain@spamcop.net> wrote:
    > >
    > > >> 5. What is the difference between tar and ufsdump?
    > > >
    > > >ufsdump is the standard backup utility. With it's brother ufsrestore,
    > > >you can backup and restore an entire system onto tape. It backs up by
    > > >filesystem. It also can do multi-reel tapes. If you have a tape
    > > >changer configured to eject a tape and insert the next tape in "stack",
    > > >ufsdump has a switch to eject the tape and wait until the next to be
    > > >inserted into the drive. There's a static version of ufs{dump,restore}
    > > >and it's also on the Solaris install CD so you can boot from CD, format
    > > >and layout a dead system disk, and do restores to the filesystems.
    > > >
    > > >tar is a tape _archiving_ utility. Functionally on a very low level, it
    > >
    > > While ufsdump is a low level backup routine (it ignores clean layering and
    > > directly read the raw disk device), tar is a high level program that correctly
    > > depends on official kernel/user-level layering.
    > >
    > > >will backup files and directories to tape. It backs up by file, so it
    > > >will walk the entire file tree if you give it "/" as the starting
    > > >directory. A while back when comparing the two utilities, some told me
    > > >that the Solaris tar won't backup special files like device files or
    > >
    > > You should not trust people who still like you to tell things that have been
    > > true in 1989. All modern tar implementations (GNU tar is not amongst them)
    > > implement at least POSIX.1-1988 TAR archives. This allows you to archive
    > > plain files, directories, raw- and block-devices, named pipes, hard- and
    > > sym-links and contiguous files.
    > >
    > > As TAR is a high level utility, it cannot tell sparse files from other plain
    > > files. There are two exceptions: GNU tar and star.
    > > GNU tar is only able to guess where the hoes are. Star may also guess but on
    > > old Solaris versions that support to read the hole list, this is supported.
    > >
    > > >"sparse" files which have big holes in them. I don't know if that's
    > > >changed. GNU's tar can do these things but I don't know if it will
    > >
    > > GNU tar will not handle sparse files that span more than media correctly.
    > >
    > > >correctly backup and restore ACL's which Solaris' tar will do. There a
    > >
    > > Star also implements support for ACLs.
    > >
    > > >third-party version of tar called star out there written and supported
    > > >in Germany. I'm sure the developer will jump in and describe it's
    > > >features more fully. I don't know for certain if Solaris' tar will do
    > > >multi-volume tapes.
    > >
    > > It does if you set up the media size in /etc/default/tar
    > >
    > > >I'm sure someone will jump in if I missed something or got it just plain
    > > >wrong...
    > >
    > > Star is half the way to support true incremental backups as ufsdump does.
    > > It is the only tar implementation that implements support for all inode
    > > properties (like ufsdump) on top of the POSIX.1-2001 extended tar
    > > format (called pax) - but note that there is currently no 'pax' command that
    > > supports the PAX archive format .-)

    > 1. to label a tape? write "tape1", "tape2", etc to the tape.

    Well to answer number one, how do you want to write to tape? Do you
    want the tape to rewind after you write to it or not? Do you want to
    write in a certain block size? etc?

    > 2. to tell whether a tape is blank (no data)?

    To answer question number two, how large are your data files,
    and what type tape are your writting to. It's common to use the -t
    option to show data on tape, if any is present.

    If you see nothing after applying tar -t then there is nothing on the
    tape.

  • Next message: Douglas O'Neal: "Re: remote access KVM switch"

    Relevant Pages

    • Re: tape command for solaris 8
      ... >> directly read the raw disk device), tar is a high level program that correctly ... >> old Solaris versions that support to read the hole list, ... how do you want to write to tape? ...
      (comp.unix.solaris)
    • Re: Questions on manipulating tape media
      ... How could I append a file on the tape? ... tar file, not to a device like rmt0. ... tape devices because such devices do not support the addition of ...
      (comp.unix.aix)
    • Re: checkpoint 8GB limit (HP-UX)
      ... standard tar header definition can't track size info above 8gb. ... format or other options that allow these archives to work, ... support "largefiles", but the utilities to manage them haven't caught ... If, in fact the OP has a single file>8GB, spreading across multiple ...
      (comp.databases.ingres)
    • Re: How to untar .tar.gz when you dont have "-z" option?
      ... > Sounds like you're using an option that tar doesn't know. ... just like it doesn't support the "z" option ... [BASH] ... Following are the error messages the code generated: ...
      (comp.unix.admin)
    • Re: Tar problem, large file
      ... Then the "other tar" has not been updated since 1995 and is non-largefile ... Historic tar implementations support files < 2 GB. ... Sun tar -E gives a Sun Proprietary enhancement for larger files. ...
      (comp.unix.solaris)