rewinding a disk drive takes too long

[Garance A Drosihn]

At 11:13 PM +0100 1/17/04, Poul-Henning Kamp wrote:
>In message <E1Ahyej-0000OI-5l at psg.com>, Randy Bush writes:
>  >
>>btw, what i forgot to say was
>>   o source system is current as of yesterday
>>   o dest system is stable as of today
>  >  o until the last upgrade to the stable dest, dump would
>  >    never complete!  it always got to the same point, 86%,
>  >     and then hung
>
>This is actually a pretty normal thing, dump is not very good at
>predicting the size of a dump if the filesystem is live (and I
>belive in a few other circumstances as well)
>
>Largest number I've seen recently was -250% :-)

Why would dump have trouble predicting the size of a "L"
filesystem?  If "L" is specified (and it apparently was in
this example), then wouldn't dump be working off of a static
snapshot of the filesystem?

-- 
Garance Alistair Drosehn            =   gad at gilead.netel.rpi.edu
Senior Systems Programmer           or  gad at freebsd.org
Rensselaer Polytechnic Institute    or  drosih at rpi.edu