On Sat, Aug 28, 2010 at 8:19 AM, Ray Van Dolson <rvandol...@esri.com> wrote: > On Sat, Aug 28, 2010 at 05:50:38AM -0700, Eff Norwood wrote: >> I can't think of an easy way to measure pages that have not been consumed >> since it's really an SSD controller function which is obfuscated from the >> OS, and add the variable of over provisioning on top of that. If anyone >> would like to really get into what's going on inside of an SSD that makes it >> a bad choice for a ZIL, you can start here: >> >> http://en.wikipedia.org/wiki/TRIM_%28SSD_command%29 >> >> and >> >> http://en.wikipedia.org/wiki/Write_amplification >> >> Which will be more than you might have ever wanted to know. :) > > So has anyone on this list actually run into this issue? Tons of > people use SSD-backed slog devices... > > The theory sounds "sound", but if it's not really happening much in > practice then I'm not too worried. Especially when I can replace a > drive from my slog mirror for a $400 or so if problems do arise... (the > alternative being much more expensive DRAM backed devices)
Presumably this problem is being worked... http://hg.genunix.org/onnv-gate.hg/rev/d560524b6bb6 Notice that it implements: 866610 Add SATA TRIM support With this in place, I would imagine a next step is for zfs to issue TRIM commands as zil entries have been committed to the data disks. -- Mike Gerdts http://mgerdts.blogspot.com/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
