selfjungle Just another WordPress weblog

zfs set ditto blocks after file system creation

"The copies property works for all new writes, so I recommend that you set that policy when you create the file system or immediately after you create a zpool." [1]

So how can you force a complete reread-rewrite?
With (non-incremental) backup and restore:

# settings properties won't work:
zfs set copies=2 POOL/FS
zfs snapshot SNAPSHOT
zfs send SNAPSHOT | xz --threads=12 --verbose > FILE.img.xz
zfs destoy POOL/FS
xz --threads=12 --decompress --verbose  FILE.img.xz -c | zfs receive POOL/FS

# so you have to create & override a new FS with copies=2
zfs snapshot SNAPSHOT
zfs send SNAPSHOT | xz --threads=12 --verbose > FILE.img.xz
zfs destoy POOL/FS
zfs create ... -o copies=2  POOL/FS
xz --threads=12 --decompress --verbose  FILE.img.xz -c | zfs receive POOL/FS -F

[1] https://blogs.oracle.com/relling/entry/zfs_copies_and_data_protection