1 '\" te
2 .\" Copyright (c) 2012 by Delphix. All rights reserved.
3 .\" The contents of this file are subject to the terms of the Common Development
4 .\" and Distribution License (the "License"). You may not use this file except
5 .\" in compliance with the License. You can obtain a copy of the license at
6 .\" usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.
7 .\"
8 .\" See the License for the specific language governing permissions and
9 .\" limitations under the License. When distributing Covered Code, include this
10 .\" CDDL HEADER in each file and include the License file at
11 .\" usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this
12 .\" CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your
13 .\" own identifying information:
14 .\" Portions Copyright [yyyy] [name of copyright owner]
15 .TH ZPOOL-FEATURES 5 "Mar 16, 2012"
16 .SH NAME
17 zpool\-features \- ZFS pool feature descriptions
18 .SH DESCRIPTION
19 .sp
20 .LP
21 ZFS pool on\-disk format versions are specified via "features" which replace
22 the old on\-disk format numbers (the last supported on\-disk format number is
180 l l .
181 GUID com.delphix:empty_bpobj
182 READ\-ONLY COMPATIBLE yes
183 DEPENDENCIES none
184 .TE
185
186 This feature increases the performance of creating and using a large
187 number of snapshots of a single filesystem or volume, and also reduces
188 the disk space required.
189
190 When there are many snapshots, each snapshot uses many Block Pointer
191 Objects (bpobj's) to track blocks associated with that snapshot.
192 However, in common use cases, most of these bpobj's are empty. This
193 feature allows us to create each bpobj on-demand, thus eliminating the
194 empty bpobjs.
195
196 This feature is \fBactive\fR while there are any filesystems, volumes,
197 or snapshots which were created after enabling this feature.
198 .RE
199
200 .SH "SEE ALSO"
201 \fBzpool\fR(1M)
|
1 '\" te
2 .\" Copyright (c) 2012 by Delphix. All rights reserved.
3 .\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
4 .\" The contents of this file are subject to the terms of the Common Development
5 .\" and Distribution License (the "License"). You may not use this file except
6 .\" in compliance with the License. You can obtain a copy of the license at
7 .\" usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.
8 .\"
9 .\" See the License for the specific language governing permissions and
10 .\" limitations under the License. When distributing Covered Code, include this
11 .\" CDDL HEADER in each file and include the License file at
12 .\" usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this
13 .\" CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your
14 .\" own identifying information:
15 .\" Portions Copyright [yyyy] [name of copyright owner]
16 .TH ZPOOL-FEATURES 5 "Mar 16, 2012"
17 .SH NAME
18 zpool\-features \- ZFS pool feature descriptions
19 .SH DESCRIPTION
20 .sp
21 .LP
22 ZFS pool on\-disk format versions are specified via "features" which replace
23 the old on\-disk format numbers (the last supported on\-disk format number is
181 l l .
182 GUID com.delphix:empty_bpobj
183 READ\-ONLY COMPATIBLE yes
184 DEPENDENCIES none
185 .TE
186
187 This feature increases the performance of creating and using a large
188 number of snapshots of a single filesystem or volume, and also reduces
189 the disk space required.
190
191 When there are many snapshots, each snapshot uses many Block Pointer
192 Objects (bpobj's) to track blocks associated with that snapshot.
193 However, in common use cases, most of these bpobj's are empty. This
194 feature allows us to create each bpobj on-demand, thus eliminating the
195 empty bpobjs.
196
197 This feature is \fBactive\fR while there are any filesystems, volumes,
198 or snapshots which were created after enabling this feature.
199 .RE
200
201 .sp
202 .ne 2
203 .na
204 \fB\fBlz4_compress\fR\fR
205 .ad
206 .RS 4n
207 .TS
208 l l .
209 GUID org.illumos:lz4_compress
210 READ\-ONLY COMPATIBLE no
211 DEPENDENCIES none
212 .TE
213
214 \fBlz4\fR is a high-performance real-time compression algorithm that
215 features significantly faster compression and decompression as well as a
216 higher compression ratio than the older \fBlzjb\fR compression.
217 Typically, \fBlz4\fR compression is approximately 50% faster on
218 compressible data and 200% faster on incompressible data than
219 \fBlzjb\fR. It is also approximately 80% faster on decompression, while
220 giving approximately 10% better compression ratio.
221
222 When the \fBlz4_compress\fR feature is set to \fBenabled\fR, the
223 administrator can turn on \fBlz4\fR compression on any dataset on the
224 pool using the \fBzfs\fR(1M) command. Please note that doing so will
225 immediately activate the \fBlz4_compress\fR feature on the underlying
226 pool (even before any data is written). Since this feature is not
227 read-only compatible, this operation will render the pool unimportable
228 on systems without support for the \fBlz4_compress\fR feature. At the
229 moment, this operation cannot be reversed. Booting off of
230 \fBlz4\fR-compressed root pools is supported.
231
232 .RE
233
234 .SH "SEE ALSO"
235 \fBzpool\fR(1M)
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