From ffcb1b9c2c9bed8a25fe91c4aee4e0ae56c55896 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 13 Apr 2011 18:26:39 +0000 Subject: Improve the discard documentation. Also improve discard code in pv_manip.c to properly account for case when pe_start=0 and the first physical extent is to be released (currently skip the first extent to avoid discarding the PV label). --- doc/example.conf.in | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'doc/example.conf.in') diff --git a/doc/example.conf.in b/doc/example.conf.in index cf318553..dfc2c701 100644 --- a/doc/example.conf.in +++ b/doc/example.conf.in @@ -152,11 +152,15 @@ devices { # pv_min_size = 2048 pv_min_size = 512 - # Issue discards to an LV's underlying PV(s) when the LV is removed. - # Discards inform the storage that a region is no longer in use. If set + # Issue discards to a logical volumes's underlying physical volume(s) when + # the logical volume is no longer using the physical volumes' space (e.g. + # lvremove, lvreduce, etc). Discards inform the storage that a region is + # no longer in use. Storage that supports discards advertise the protocol + # specific way discards should be issued by the kernel (TRIM, UNMAP, or + # WRITE SAME with UNMAP bit set). Not all storage will support or benefit + # from discards but SSDs and thinly provisioned LUNs generally do. If set # to 1, discards will only be issued if both the storage and kernel provide - # support. Not all storage will support or benefit from discards but SSDs - # or thinly provisioned LUNs generally do. + # support. # 1 enables; 0 disables. issue_discards = 0 } -- cgit