I am completely thrilled with these responses. Unfortunately I probably wont have time to code review anytime soon the consideration given to the admin interface seems particularly robust. :)
Sent from my iPhone > On Aug 7, 2016, at 1:31 PM, Saso Kiselkov <[email protected]> wrote: > >> On 8/7/16 8:07 PM, Garrett D'Amore wrote: >> historically some ssds have performed worse with trim as they do >> some expensive operations. i have not looked at the webrev yet >> but are there tunables or an administrative interface to this? > > By default, everything is off, so there are no performance > implementations "out of the box". The administrative interfaces are, either: > > * enabling automatic trimming after deleting data: > # zpool set autotrim=on <poolname> > > * manually initiating a single full-pool trim (running through > all the free space on a pool and trimming it): > # zpool trim <poolname> > > Automatic trim is as the name implies: fully automatic. You just delete > data and ZFS will at some later point, if the blocks have not been > reused, simply trim those blocks out. > > Manual trim behaves much like a scrub. It has an adjustable rate (in > bytes/sec) and can be monitored through "zpool status" or stopped at any > time via "zpool trim -s <poolname>". > >> how diverse in terms of ssds has this been tested with? > > We've tested primarily with Sandisk SAS SSDs, mainly the Optimus line > and on some pretty high-end kit (Sandisk's INFINIFLASH). > >> are there performance implications observed? > > Yes, this is detailed in the manpage. In general, Optimus 1 takes poorly > to automatic trim and can suffer a write throughput limitation when lots > of deletes are going on. On Optimus 2 and the IF100 the performance > impact was much smaller (measurable, but really not much). > > In general, the manpage suggests a "test and see what works" approach. > Try autotrim=on and see if it affects performance on your system. If it > doesn't, leave autotrim on. If it does, disable autotrim and use manual > trim during a maintenance window to still get most of the used block > recovery benefits. > > Cheers, > -- > Saso > ------------------------------------------- openzfs-developer Archives: https://www.listbox.com/member/archive/274414/=now RSS Feed: https://www.listbox.com/member/archive/rss/274414/28015062-cce53afa Modify Your Subscription: https://www.listbox.com/member/?member_id=28015062&id_secret=28015062-f966d51c Powered by Listbox: http://www.listbox.com
