Replication with compression

B

Benoît Fontaine

Member
Apr 12, 2018
31
5
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Hi,
Is there a way through proxmox (pve 5) to replicate with compression ?

Something like :
Code: 
zfs send -Rpvi tank/vm-100-disk-0@__replicate_100-0_1538395933_ tank/vm-100-disk-0@__replicate_100-0_1538474876_ | bzip2 -c | ssh node2 "bzcat | zfs recv -F tank/vm-100-disk-0"
 
man zfs:
Code: 
       -c, --compressed
           Generate a more compact stream by using compressed WRITE records for blocks which are compressed on disk and in memory (see the compression property for
           details).  If the lz4_compress feature is active on the sending system, then the receiving system must have that feature enabled as well.  If the
           large_blocks feature is enabled on the sending system but the -L option is not supplied in conjunction with -c, then the data will be decompressed before
           sending so it can be split into smaller block sizes.

also dedup might work:
Code: 
       -D, --dedup
           Generate a deduplicated stream.  Blocks which would have been sent multiple times in the send stream will only be sent once.  The receiving system must also
           support this feature to receive a deduplicated stream.  This flag can be used regardless of the dataset's dedup property, but performance will be much better
           if the filesystem uses a dedup-capable checksum (for example, sha256).
 
In addition to @Knuuut s answer:

- bzip2 is single thread bound, all ZFS operations are parallelized including the compression if done on the ZFS side
- SSH also includes a compression option, please refer to the manpage
- SSH is also encryption bound to one cpu core, so the best way to load off data is to have parallel compression and parallel encryption
 
Thanks, zfs send -c seems very useful. But is there a way to configure this option through proxmox web interface ? Or in /etc/pve/replication.cfg ?
 
I found a solution : update the file /usr/share/perl5/PVE/Storage/ZFSPoolPlugin.pm line 672 (pve 5.2-9):
replace
Code: 
    my $cmd = ['zfs', 'send', '-Rpv'];
by
Code: 
    my $cmd = ['zfs', 'send', '-RpvcD'];
It is not necessary to restart any service.

It's not a very clean solution (and it can possibly be deleted if you update your proxmox), but it works.
I think that SSH compression can be useful in addition.
 
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