On Fri, Aug 16, 2002 at 10:07:54AM +0300, Conny Gyllendahl wrote:
> Now for my last question for this time: what are the pros and cons, if
> any, for using tar or (ufs)dump? Are there any reasons or situtations
> for choosing one over the other?

You say "ufs(dump)", so I'm assuming recent Solaris.  The calculation
is different for Linux.

ufsdump plus:

    - Gets all file system/file attributes, period, no ifs ands or
      buts, even ones you don't know are there.  :-)

    - Does not touch atime on files.

    - Does not require running as root.

    - In my experience, on file systems with large numbers of small
      files, estimates and incrementals are much faster than GNU tar.

ufsdump minus:

    - No exclude list.

    - No splitting the file system.

    - Data is not portable to other OS's.

tar plus:

    - Flexibility.  Excludes, splitting.

    - 100% portable, ubiquitous.  (But see also tar minus)

tar minus:

    - Touches atime.

    - In my experience, on file systems with large numbers of small
      files, estimates and incrementals can take a long time.

    - "Portable, but": GNU tar output with very long paths/names is
      only guaranteed to be readable by another GNU tar of "similar"
      version.  Reading with non-GNU tar (or older GNU tar) may
      generate errors, or garbled paths/names.  Depending on the
      versions involved, things get interesting at name lengths of 100
      or 256, and path lengths of 256 or 1024.  This is a very minor
      minus, you just need to be aware.

    - Has to run as root (no, I don't lose any sleep worrying about
      runtar exploits! :-)

Speed folklore:

    In my experience, on full backups, on modern Solaris kit, GNU tar
    is a bit faster than ufsdump, *not* slower.  Disks have gotten a
    lot faster (helps the more-random seeks that tar has to do), ufs
    and the processors have gotten faster (so ufs isn't "in the way"
    any more), and ufsdumps's initial mapping (wonderful for
    'ufsrestore -i') is just time down the drain from amanda's
    POV.

There, no religion here, I think.  Look at the plus/minus lists and
make up your own mind.  As the Perl folk say, TMTOWTDI.

-- 
Jay Lessert                               jay_lessert AT accelerant DOT net
Accelerant Networks Inc.                       (voice)1.503.439.3461
Beaverton OR, USA                                (fax)1.503.466.9472