Leonardo Francalanci wrote:
Hi,
regarding ZFS compression method: what happens when a compressed file is
udpated/appended? Is it ALL un-compressed first, updated/appended and
then re-compressed? Or only the affected blocks are uncompressed and
then recompressed?
ZFS does NOT compress files. It compresses the individual blocks that
are written to comprise the file.
What this means is if you have a 10G file and you need to change one
small part in the middle you seek(2) to that point, read(2) the data
make your change to your in memory copy and write(2) it back out again.
ZFS will update (and recompress) only those blocks that actual need to
get changed.
--
Darren J Moffat
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