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Matthew Ahrens fc6700425a Deprecate deduplicated send streams
Dedup send can only deduplicate over the set of blocks in the send
command being invoked, and it does not take advantage of the dedup table
to do so. This is a very common misconception among not only users, but
developers, and makes the feature seem more useful than it is. As a
result, many users are using the feature but not getting any benefit
from it.

Dedup send requires a nontrivial expenditure of memory and CPU to
operate, especially if the dataset(s) being sent is (are) not already
using a dedup-strength checksum.

Dedup send adds developer burden. It expands the test matrix when
developing new features, causing bugs in released code, and delaying
development efforts by forcing more testing to be done.

As a result, we are deprecating the use of `zfs send -D` and receiving
of such streams.  This change adds a warning to the man page, and also
prints the warning whenever dedup send or receive are used.

In a future release, we plan to:
1. remove the kernel code for generating deduplicated streams
2. make `zfs send -D` generate regular, non-deduplicated streams
3. remove the kernel code for receiving deduplicated streams
4. make `zfs receive` of deduplicated streams process them in userland
   to "re-duplicate" them, so that they can still be received.

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #7887
Closes #10117
2020-05-12 10:53:32 -07:00
.github Fix typos 2020-01-22 13:49:00 -08:00
cmd Deprecate deduplicated send streams 2020-05-12 10:53:32 -07:00
config Fix CONFIG_MODULES=no Linux kernel config 2020-05-12 10:53:32 -07:00
contrib Fix zfs-functions packaging bug 2020-05-12 10:53:32 -07:00
etc Fix zfs-functions packaging bug 2020-05-12 10:53:32 -07:00
include Deprecate deduplicated send streams 2020-05-12 10:53:32 -07:00
lib Deprecate deduplicated send streams 2020-05-12 10:53:32 -07:00
man Deprecate deduplicated send streams 2020-05-12 10:53:32 -07:00
module Linux 5.5 compat: blkg_tryget() 2020-05-12 10:53:32 -07:00
rpm Canonicalize Python shebangs 2020-01-22 13:49:00 -08:00
scripts Fix typos 2020-01-22 13:49:00 -08:00
tests Restore :: in Makefile.am 2020-05-12 10:53:32 -07:00
udev Restore :: in Makefile.am 2020-05-12 10:53:32 -07:00
.gitignore Adapt gitignore for modules 2020-01-22 13:49:05 -08:00
.gitmodules Add zimport.sh compatibility test script 2014-02-21 12:10:31 -08:00
.travis.yml Add .travis.yml 2017-11-13 09:18:18 -08:00
AUTHORS Update build system and packaging 2018-05-29 16:00:33 -07:00
autogen.sh Cause autogen.sh to fail if autoreconf fails 2018-07-06 09:27:37 -07:00
CODE_OF_CONDUCT.md Add CODE_OF_CONDUCT.md 2019-04-30 10:58:45 -07:00
configure.ac Fix zfs-functions packaging bug 2020-05-12 10:53:32 -07:00
copy-builtin Allow copy-builtin to work with modified sources 2018-10-17 12:06:05 -07:00
COPYRIGHT Update build system and packaging 2018-05-29 16:00:33 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am Perform KABI checks in parallel 2020-01-22 13:49:01 -08:00
META Tag zfs-0.8.3 2020-01-22 13:51:17 -08:00
NEWS Add NEWS file 2018-09-18 12:03:47 -07:00
NOTICE Update build system and packaging 2018-05-29 16:00:33 -07:00
README.md Explicitly state supported Linux versions 2018-05-30 20:11:19 -07:00
TEST Update build system and packaging 2018-05-29 16:00:33 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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ZFS on Linux is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community.

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Official Resources

Installation

Full documentation for installing ZoL on your favorite Linux distribution can be found at our site.

Contribute & Develop

We have a separate document with contribution guidelines.

Release

ZFS on Linux is released under a CDDL license.
For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported kernel versions.