[H-GEN] Tape Drives

Jason Henry Parker jasonp at uq.net.au
Tue Jan 8 16:08:28 EST 2002


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Bruce Campbell <bc at humbug.org.au> writes:

> Your milage may vary, but in a serious backup regime, you have one or more
> of:
> 
> 	serious cpu to do decent software compression inline
> 	a staging area to put compressed images before dumping to tape
> 		(read, oodles of spare diskspace)
> 	hardware compression on the tape drive.
> 	Lots and lots of tapes.

> Decide whether you want speed, long-term reliability or small tape usage.
> Two of these at the same time is usually not attainable ;)

Well, obviously my mileage is varying.  I've run the same backup
system with and without software compression instead of hardware
compression[1].  The data speed writing to tape has not decreased.
The drive also is notably not rewinding the tape and resuming writing.

It probably helps that I have 1) and 2) of the list named above
(though I doubt AMANDA uses the holding disk unless there's an
error).

Long-term reliability is a bit of a worry, though.  How would I
reasonably go about testing it?  While I've never had a tape fail:

 (a) I've not had much call to use them, and getting enough time to
     run verifies every day is a bit much.  I suppose I could test one
     tape per slightly-less-than-the-dumpcycle.

 (b) The backup system as a whole probably has not been running long
     enough.  The oldest tapes I have in regular use aren't even a
     year old.

jason

[1] : And, oh, yes, I *did* run the backups with software and hardware
      compression, once.  It was a godawful mess.
-- 
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