As new compression algorithms are added to ZFS, it could be useful for
people to recompress data with new algorithms. There is currently no
mechanism to do this aside from copying the data manually into a new
filesystem with the new algorithm enabled. This tool allows the
transformation to happen through zfs send, allowing it to be done
efficiently to remote systems and in an incremental fashion.
A new zstream command is added that decompresses WRITE records and
then recompresses them with a provided algorithm, and then re-emits
the modified send stream. It may also be possible to re-compress
embedded block pointers, but that was not attempted for the initial
version.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes#14106
It can be used to repair a ZFS file system corrupted by ZFS bug #12762.
Use it like this:
zfs send -c <DS> | \
zstream decompress <OBJECT>,<OFFSET>[,<COMPRESSION_ALGO>] ... | \
zfs recv <DST_DS>
Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Signed-off-by: Alan Somers <asomers@gmail.com>
Sponsored-by: Axcient
Workaround for #12762Closes#13256
Adding a new subcommand to zstream called token. This
now allows users to decode a resume token to retrieve the toname
field. This can be useful for tools that need this information.
The syntax works as follows zstream token <resume_token>.
Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Paul Zuchowski <pzuchowski@datto.com>
Signed-off-by: Tony Perkins <tperkins@datto.com>
Closes#10558
Deduplicated send and receive is deprecated. To ease migration to the
new dedup-send-less world, the commit adds a `zstream redup` utility to
convert deduplicated send streams to normal streams, so that they can
continue to be received indefinitely.
The new `zstream` command also replaces the functionality of
`zstreamdump`, by way of the `zstream dump` subcommand. The
`zstreamdump` command is replaced by a shell script which invokes
`zstream dump`.
The way that `zstream redup` works under the hood is that as we read the
send stream, we build up a hash table which maps from `<GUID, object,
offset> -> <file_offset>`.
Whenever we see a WRITE record, we add a new entry to the hash table,
which indicates where in the stream file to find the WRITE record for
this block. (The key is `drr_toguid, drr_object, drr_offset`.)
For entries other than WRITE_BYREF, we pass them through unchanged
(except for the running checksum, which is recalculated).
For WRITE_BYREF records, we change them to WRITE records. We find the
referenced WRITE record by looking in the hash table (for the record
with key `drr_refguid, drr_refobject, drr_refoffset`), and then reading
the record header and payload from the specified offset in the stream
file. This is why the stream can not be a pipe. The found WRITE record
replaces the WRITE_BYREF record, with its `drr_toguid`, `drr_object`,
and `drr_offset` fields changed to be the same as the WRITE_BYREF's
(i.e. we are writing the same logical block, but with the data supplied
by the previous WRITE record).
This algorithm requires memory proportional to the number of WRITE
records (same as `zfs send -D`), but the size per WRITE record is
relatively low (40 bytes, vs. 72 for `zfs send -D`). A 1TB send stream
with 8KB blocks (`recordsize=8k`) would use around 5GB of RAM to
"redup".
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#10124Closes#10156
