MFV r267565:

4757 ZFS embedded-data block pointers ("zero block compression")
4913 zfs release should not be subject to space checks

MFC after:	2 weeks

1 files changed, 29 insertions, 1 deletions

diff --git a/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7 b/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7
index 5560de9..d0f3ab2 100644
--- a/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7
+++ b/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7
@@ -23,7 +23,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 23, 2014
+.Dd June 30, 2014
 .Dt ZPOOL-FEATURES 7
 .Os
 .Sh NAME
@@ -396,6 +396,34 @@ This feature becomes
 as soon as it is enabled and will
 never return to being
 .Sy enabled .
+.It Sy embedded_data
+.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:embedded_data"
+.It GUID Ta com.delphix:embedded_data
+.It READ\-ONLY COMPATIBLE Ta no
+.It DEPENDENCIES Ta none
+.El
+.Pp
+This feature improves the performance and compression ratio of
+highly-compressible blocks.
+Blocks whose contents can compress to 112 bytes
+or smaller can take advantage of this feature.
+.Pp
+When this feature is enabled, the contents of highly-compressible blocks are
+stored in the block "pointer" itself
+.Po a misnomer in this case, as it contains
+the compresseed data, rather than a pointer to its location on disk
+.Pc .
+Thus
+the space of the block
+.Pq one sector, typically 512 bytes or 4KB
+is saved,
+and no additional i/o is needed to read and write the data block.
+.Pp
+This feature becomes
+.Sy active
+as soon as it is enabled and will
+never return to being
+.Sy enabled .
 .El
 .Sh SEE ALSO
 .Xr zpool 8