From 063edd7fd88bdcb17ea286899788fef09459cdb3 Mon Sep 17 00:00:00 2001 From: Richard Laager Date: Thu, 18 Apr 2019 20:21:09 -0500 Subject: [PATCH] Document that hole_birth is effectively useless The first sentence of this commit comes from the wiki, and was originally written by: Rich Ercolani with changes by: Tom Caputi Reviewed-by: Tom Caputi Reviewed-by: Brian Behlendorf Signed-off-by: Richard Laager Closes #8641 Closes #8642 --- man/man5/zpool-features.5 | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/man/man5/zpool-features.5 b/man/man5/zpool-features.5 index 1df7f0f76..8893d151d 100644 --- a/man/man5/zpool-features.5 +++ b/man/man5/zpool-features.5 @@ -383,6 +383,14 @@ READ\-ONLY COMPATIBLE no DEPENDENCIES enabled_txg .TE +This feature has/had bugs, the result of which is that, if you do a +\fBzfs send -i\fR (or \fB-R\fR, since it uses \fB-i\fR) from an affected +dataset, the receiver will not see any checksum or other errors, but the +resulting destination snapshot will not match the source. Its use by +\fBzfs send -i\fR has been disabled by default. See the +\fBsend_holes_without_birth_time\fR module parameter in +zfs-module-parameters(5). + This feature improves performance of incremental sends (\fBzfs send -i\fR) and receives for objects with many holes. The most common case of hole-filled objects is zvols. -- 2.40.0