[ale] Bacula

[Jeff Hubbs]

Dow -

I managed to get an answer to my own question from the Web site's docs. 
They make two Free Software utilities for listing and extracting tape
contents - a useful compromise.

- Jeff

On Fri, 2004-03-19 at 15:06, Dow Hurst wrote:
> You know, I really don't know how xfsdump writes the data.  I know this:
> 
> It writes the inventory at the beginning of the tape.
> It writes 500Mb files of data at a time.
> 
> The main reason I use it is that it allows recovery of a single file quickly 
> by scanning the inventory of what is on the tape and knowing exactly where 
> that file is.  A single 500Mb file corruption doesn't ruin the whole backup. 
> It understands the XFS filesystem.  It was free. :)
> 
> It is supposed to be able to use two or more identical tape drives to backup 
> in simultaneous streams to both drives.
> 
> I've heard that DDS tapes are not robust compared to DLT.  I've never had DLT 
> to use so don't know what I am missing.  However, the College of Science and 
> Math is adding a 20 tape autochanger backup running BruPro.  I can make use of 
> 4 tape slots and it uses DLT!  So, this may be my solution, with the current 
> drive backing up as a backup to the main backup.
> Dow
> 
> 
> Stephan Uphoff wrote:
> > Dow Hurst wrote:
> > 
> >>I am currently concerned with our backup process right now 
> >>since we've outgrown the DDS3 tape drive I have.  It takes 10-11 compressed 
> >>xfsdump formatted DDS3 tapes to get our single filesystem of everyone's home 
> >>directories backed up.  Shoving that many tapes at minimum 6 hours per tape 
> >>ends up being practically a week for a single level zero backup.  I need 
> >>another identical tape drive so I can stream to two drives.
> > 
> > 
> > Mhhh ... I think a DDS3 drive writes 1.2MB/s (2.4 compresses) to a tape
> > that is 12G (24G compressed). A streaming write of the whole tape should
> > take less than 3 hours.
> > Unless I have the wrong data this indicates that your xfsdump is not streaming.
> > ( Do you head the tape stopping,rewinding a bit, starting ..?)
> > It would probably be worthwhile to play with the tape buffering values and
> > to research dd like programs with deep buffers.
> > Since DDS tapes survive only a really small number of head-passes streaming also
> > helps preserving them.
> > 
> > If you need to buy a tape drive look for DDS alternatives - they are a bit
> > more expensive - but a lot more reliable,faster and have decent capacities (DLT,..)
> > 
> > 	Stephan 
> > 
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