mirror_zfs/cmd
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
..
arc_summary arc_summary: Make get_descriptions per platform 2020-02-27 17:15:06 -08:00
arcstat Changed decimals to integers in the arcstat script 2020-03-18 11:50:45 -07:00
dbufstat Detect if sed supports --in-place 2019-10-16 19:19:48 -07:00
fsck_zfs Fix typos in cmd/ 2019-08-30 09:43:30 -07:00
mount_zfs OpenZFS restructuring - libspl 2019-10-02 10:39:48 -07:00
raidz_test Add AltiVec RAID-Z 2020-01-23 11:01:24 -08:00
vdev_id Fix typos in cmd/ 2019-08-30 09:43:30 -07:00
zdb Improve zfs destroy performance with zio_t-free zio_free() 2020-02-28 14:49:44 -08:00
zed Systemd mount generator: Generate noauto units; add control properties 2020-02-14 15:32:55 -08:00
zfs Deprecate deduplicated send streams 2020-03-18 13:31:10 -07:00
zgenhostid bash scripts: use /usr/bin/env for bash shebangs 2020-02-10 13:13:46 -08:00
zhack Add zfs_file_* interface, remove vnodes 2019-11-21 09:32:57 -08:00
zinject Remove ECKSUM alias in zinject 2019-11-01 10:31:42 -07:00
zpool Add trim support to zpool wait 2020-03-04 15:07:11 -08:00
zstreamdump fix zstreamdump -C 2020-02-13 11:24:57 -08:00
ztest libzfs: Fix bounds checks for float parsing 2020-03-16 11:56:29 -07:00
zvol_id OpenZFS restructuring - libspl 2019-10-02 10:39:48 -07:00
zvol_wait zvol_wait should ignore redacted zvols 2019-11-06 10:51:19 -08:00
Makefile.am Isolate code specific to Linux in cmd/ 2019-11-11 09:24:04 -08:00