On Tuesday 12 April 2005 10:50, Salada, Duncan S. wrote:
>Actually, I'm not using a holding disk at all. I had no idea that I
> could be shortening the life of the tape drive by not using one.
> So, that's probably the source of my problem then?
I expect it is, Duncan. One really should have a holding disk area
that is capable of holding the 2 or 3 largest disklist entries,
preferably lots more, and thats easy when todays commodity drive is a
120GB or so drive. I have about a 25GB area, free space on a
partition and this, for the dle's I have constructed, is only used to
maybe the 22GB free at its peak use. But then I've tried to follow
my own advice in that most of my disklist entries (nearly 50 of them)
are all fairly smallish, giving amanda as much help in her balanceing
action as possible.
The idea behind the holding disk (which really shouldn't be on the
same controller as the disk drive because of bus contention issues)
is that if the drive is waiting on data and stops, it will not
restart until the next file to be written is wholely in the holding
disk, at which point the copy can then take place at the drives
natural speed.
By carefull choice of the priority string in your amanda.conf, one can
often hit a point where once the drive starts, it will run non-stop
until the nightly run is done. I try to put the biggest ones on the
front of the tape, and by the time the first one is cached and
written, many of the rest are waiting, so the drive never stops
between files.
Shoe-shining the drive because its running out of data, making it
stop, backup to the last good block written, & repeat at 2 (or less)
second intervals, is very hard on both the drives mechanics and the
heads, but is also making a one pass write into a many pass write,
with a severe reduction in the life of the tape.
When you do setup the holding disk, be sure and add a line in your
amanda.conf thats says something like 'reserved 30%', otherwise it
can only be used in the event of a tape problem for incrementals, no
fulls. With it in there, then fulls can proceed as normal, piling up
in the holding area until its down to 30% of its original capacity
remaining. It might give you an extra day or 2 to solve a tape drive
problem in that event.
[...]
--
Cheers Duncan, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
99.34% setiathome rank, not too shabby for a WV hillbilly
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Copyright 2005 by Maurice Eugene Heskett, all rights reserved.
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