mirror_zfs/include
Matthew Ahrens 652bdc9b0e
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
2020-03-18 13:31:10 -07:00
..
os Improve performance of zio_taskq_member 2020-03-03 10:29:38 -08:00
sys Separate warning for incomplete and corrupt streams 2020-03-17 10:30:33 -07:00
.gitignore OpenZFS restructuring - move platform specific sources 2019-09-06 11:26:26 -07:00
libnvpair.h Add JSON output support to channel programs 2018-03-19 12:40:58 -07:00
libuutil_common.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
libuutil_impl.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
libuutil.h Correct cppcheck errors 2017-09-19 12:17:29 -07:00
libzfs_core.h Add 'zfs send --saved' flag 2020-01-10 10:16:58 -08:00
libzfs_impl.h Deprecate deduplicated send streams 2020-03-18 13:31:10 -07:00
libzfs.h Add option for forcible unmounting dataset while receiving snapshot. 2020-03-17 10:08:32 -07:00
libzutil.h Colorize zpool status output 2019-12-19 16:26:07 -08:00
Makefile.am OpenZFS restructuring - move platform specific headers 2019-09-05 09:34:54 -07:00
thread_pool.h Add libtpool (thread pools) 2017-08-09 15:31:08 -07:00
zfeature_common.h Disable EDONR on FreeBSD 2019-12-05 13:10:29 -08:00
zfs_comutil.h Fix "zpool add -n" for dedup, special and log devices 2020-01-06 15:40:06 -08:00
zfs_deleg.h Remove code for zfs remap 2019-06-24 16:44:01 -07:00
zfs_fletcher.h Add AVX512BW variant of fletcher 2019-10-30 12:26:14 -07:00
zfs_namecheck.h Implement bookmark copying 2020-02-11 13:19:12 -08:00
zfs_prop.h Add zfs module feature and property info to sysfs 2018-09-02 12:09:53 -07:00