On 2018-11-28 13:58, Chris Nighswonger wrote:
On Wed, Nov 28, 2018 at 11:17 AM Austin S. Hemmelgarn
<[email protected] <mailto:[email protected]>> wrote:
Based on your configuration, your tapes are configured to store just
short of 800GB of data.
The relevant lines then are these two:
flush-threshold-scheduled 50
flush-threshold-dumped 50
I misunderstood the man pages there and for some reason thought that
volume referred to the holding disk. Probably because I was reading way
too fast....
In your case, I'd suggest figuring out the average amount of data you
dump each run, and then configuring things to start flushing when about
half that much data has been dumped. That will still have the taping
run in parallel with the dumping, but will give you enough of a buffer
that the taper should never have to wait for dumps to finish.
So over the last 13 runs, the:
-- smallest volume size has been 152G (19% tape capacity)
-- average volume size has been 254G (32% tape capacity)
-- largest volume size has been 612G (76% tape capacity)
So do the following values look "reasonable" based on those numbers:
flush-threshold-scheduled 25
flush-threshold-dumped 0
That should target the larger sizes which are the ones which tend to lap
into the next business day.
Probably. The extent of the experimentation I've done with these is
determining for certain that I got no performance benefits from not just
taping backups as they finished (all of my setups use vtapes on fast
storage, so there's no benefit to me not just taping dumps as they're done).
