On Sun, 25 May 2014, Jim Klimov via illumos-discuss wrote:
ZFS reservations certainly are not it - this is a way to reserve some amount of blocks from being referenced by other datasets. Without TRIM/UNMAP support, this is not a way to guarantee that such amount of blocks would be zero on disk and thus (if this is at all a criterion for a certain ssd's firmware) subject this amount of LBAs to consideration as empty for the purposes of garbage collection and RMW's of ssd pages. Thus this space would be sacrificed for no good reason - useless for other datasets, but not advancing performance nor reliability of the ssd's.
It seems like what is needed is to be able to specify the amount of unused space that zfs will leave at the end of the partition/disk. It already leaves some spare space in order to allow some slop with replacement disk sizes.
Bob -- Bob Friesenhahn [email protected], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ ------------------------------------------- illumos-discuss Archives: https://www.listbox.com/member/archive/182180/=now RSS Feed: https://www.listbox.com/member/archive/rss/182180/21175430-2e6923be Modify Your Subscription: https://www.listbox.com/member/?member_id=21175430&id_secret=21175430-6a77cda4 Powered by Listbox: http://www.listbox.com
