--On Thursday, October 30, 2003 20:25:26 +0100 Paul Bijnens <paul.bijnens AT 
xplanation DOT com> wrote:

> 
> Frank Smith wrote:
>> If you have plenty of holding disk space and no changer you might 
>> prefer to not use chg-manual and lie about your tape length. I'm sure
>> someone will correct me if I'm wrong (I don't use chg-manual), but I
> 
>   :-)
> 
> Never lie to amanda. She hates it.
> I use chg-multi (two drives) and tell manda that she can use 3 tapes
> (runtapes 3).  With these parameters Amanda writes two tapes at night,
> and dumps the rest to holdingdisk, which I flush manually on monday
> morning on the third tape. (This works also for one drive.)
> Note: you have to set the reserve parameter to something else than
> the default 100 (= reserve 100% of the holdingdisk for incrementals
> when dumping in degraded mode because you ran out of tape)
> for this work.
> 
> 
>> think with chg-manual and a small holdingdisk Amanda pauses the
>> backups while it waits for a new tape. If you run it overnight and
>> don't change tapes until the morning, part of your backups will be
>> run after you change the tape, and you may not want the load on your
>> servers and network during the day (plus your filesystems may be more
>> active). If you say your tape is much longer than it is, Amanda will
>> hit EOT and continue doing the backups to holdingdisk. You can then
>> run amflush the next morning after changing tapes without impacting
>> any other servers.
> 
> If you lie to Amanda, she might as well think that some DLE would fit
> on this exagerated tape, but which physically does not fit on the real
> tape length.  Also the newer parameter like 'taperalgo largestfit'
> would not work.

I didn't realize you could set runtapes > 1 without specifying a
changer, so your method would make better use of the tapes.
   If your DLE doesn't fit on a tape, whether you lie about the length
or not won't make it fit.  But your points are valid and I stand corrected.

Frank
   


-- 
Frank Smith                                      fsmith AT hoovers DOT com
Systems Administrator                           Voice: 512-374-4673
Hoover's Online                                   Fax: 512-374-4501