On Fri, Aug 12, 2016 at 12:38:41PM +1000, Craig Sanders wrote:
as the SSD is fast at large reads (500MB/s), I could also just cache metadata and not data. would that make sense do you think?
it might help. I used to do it and it didn't seem to do much, but that was on a low memory system with only 1GB of ARC. IIRC, I have primarycache=metadata and secondarycache=all
i should have mentioned that this was on a system with lots of background processes and cron jobs, many of which recurse directories, so lots of metadata churn. e.g. running find on a large directory (like a debian mirror) will do it. btw, i guess you've already read http://open-zfs.org/wiki/Performance_tuning also, this is a bit dated but still worth reading: https://pthree.org/2012/12/07/zfs-administration-part-iv-the-adjustable-repl... craig -- craig sanders <cas@taz.net.au>