On 3 déc. 2009, at 13:29, Bob Friesenhahn <bfrie...@simple.dallas.tx.u
s> wrote:
On Thu, 3 Dec 2009, Darren J Moffat wrote:
The answer to this is likely deduplication which ZFS now has.
The reason dedup should help here is that after the 'cat' f15 will
be made up of blocks that match the blocks of f1 f2 f3 f4 f5.
Copy-on-write isn't what helps you here it is dedup.
Isn't this only true if the file sizes are such that the
concatenated blocks are perfectly aligned on the same zfs block
boundaries they used before? This seems unlikely to me.
It's also worth noting that if the block alignment works out for the
dedup, the actual write traffic will be trivial, consisting only of
pointer references, so the heavy lifting will be the read operations.
Much depends on the contents of the files. Fixed size binary blobs
that align nicely with 16/32/64k boundaries, or variable sized text
files.
Cordialement,
Erik Ableson
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
