Thank you for the amazing tip. I also benchmarked similar results: amgtar was averaging 140MB/s with --sparse, and with sparse disabled it now averages 600MB/s. I expect this will have a huge improvement on backup times.
On Sat, 31 Aug 2024 at 10:57, Exuvo <[email protected]> wrote: > I have been trying to figure out why tar run by amanda was so much slower > than my manual tar runs. > The culprit is tar --sparse (which is on by default in amgtar) which for > me maxes out 1 CPU core and reduces tar's read speed to around 130MB/s for > me on a ZFS filesystem with 1GB files. > I turned that option off and now it can read at 500MB/s with only 30% CPU > usage. > > I suspect this will also resolve the slow read speeds i have with lots of > tiny files as tar was also capped on CPU there but i had assumed it was > blocking on IO. > > -- > Anton "exuvo" Olsson > [email protected] > >
