I think something is majorly broken with ARC, as I can't explain the behaviour I'm seeing.
Anyone else able to what I'm seeing by playing with the maxARC value?
What I don't get is:
1. changing ARC from 11GB to 600MB pushes SSD I/O back up to > 200MB/sec
2. while reading the 5.2GB file to the EVO, all is well but starts to slow to a crawl, then changing ARC does nothing (unlike 1.) but duplicating the file (Command-D) pushes SSD I/O up again...
I'd luv to get my hands on a build that ignores ARC altogether (is this programatically possible with ZFS?) and just see what happens...
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HacPro:~ madmin$ sysctl {spl,zfs}.kext_version
spl.kext_version: 1.7.0-1-g9f0861d
zfs.kext_version: 1.7.0-27-g604a07773
The pool zippy is a test pool using old 60GB Kingston SSDs as a 4 way stripe...
Hac is an X58 mobo, Xeon 4C@3GHz HT and 24GB RAM running macOS 10.13.2 on an Samsung EVO 250GB for boot and test file is a H264 TV show.