[ale] Bacula

[Dow Hurst]

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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> 

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Dow Hurst                  Office: 770-499-3428            *
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