> do you have any reference to ZFS being content-addressed storage? It's not purely content-addressed storage, but it implements deduplication in the same way venti does: http://blogs.oracle.com/bonwick/entry/zfs_dedup (the blog post offers only a high level overview, you have to dig into the code to see the implementation).
> your claim was, random access is free on ssds. and i don't see how these > numbers bolster your claim at all. Maybe my wording wasn't the best, so I'll try again. SSDs can do 100times more iops than HDDs for a given performance hit ratio. In my experience, ignoring fragmentation completely leads to average fragmentation being significantly less than 100 times worse compared to a traditional filesystem that tries hard to avoid it. In practice, I've found that a fragmented filesystem on a SSD performs at worst 10% behind the non-fragmented best case scenario. I'd trade 10% performance for significantly simpler code anytime. The phrase above is ignoring caching. I've ran ZFS for many years without a SSD and I haven't noticed the fragmentation because of very aggressive caching (see the ARC algorithm). -- Aram Hăvărneanu
