> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > boun...@opensolaris.org] On Behalf Of Ian Collins > > Add to that: if running dedup, get plenty of RAM and cache.
Add plenty RAM. And tweak your arc_meta_limit. You can at least get dedup performance that's on the same order of magnitude as performance without dedup. Cache devices don't really help dedup very much - Because each DDT stored in ARC/L2ARC takes 376 bytes, and each reference to an L2ARC entry requires 176 bytes of ARC. So in order to prevent an individual DDT entry from being evicted to disk, you must either keep the 376 bytes in ARC, or evict it to L2ARC and keep 176 bytes. This is a very small payload. A good payload would be to evict a 128k block from ARC into L2ARC, keeping the 176 bytes only in ARC. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
