On 12 April, 2010 - Bob Friesenhahn sent me these 0,9K bytes: > On Sun, 11 Apr 2010, James Van Artsdalen wrote: > >> OpenSolaris needs support for the TRIM command for SSDs. This command >> is issued to an SSD to indicate that a block is no longer in use and >> the SSD may erase it in preparation for future writes. > > There does not seem to be very much `need' since there are other ways > that a SSD can know that a block is no longer in use so it can be > erased. In fact, ZFS already uses an algorithm (COW) which is friendly > for SSDs. > > Zfs is designed for high thoughput, and TRIM does not seem to improve > throughput. Perhaps it is most useful for low-grade devices like USB > dongles and compact flash.
For flash to overwrite a block, it needs to clear it first.. so yes, clearing it out in the background (after erasing) instead of just before the timing critical write(), you can make stuff go faster. /Tomas -- Tomas Ögren, st...@acc.umu.se, http://www.acc.umu.se/~stric/ |- Student at Computing Science, University of Umeå `- Sysadmin at {cs,acc}.umu.se _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
