[ale] Bacula
Jeff Hubbs
hbbs at comcast.net
Fri Mar 19 18:40:54 EST 2004
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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> > Ale at ale.org
> > http://www.ale.org/mailman/listinfo/ale
> >
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