Very cool! Just one comment. You said: > We'll try compression level #9.
gzip-9 is *really* CPU-intensive, often for little gain over gzip-1. As in, it can take 100 times longer and yield just a few percent gain. The CPU cost will limit write bandwidth to a few MB/sec per core. I'd suggest that you begin by doing a simple experiment -- create a filesystem at each compression level, copy representative identical data to each one, and compare space usage. My guess is that you'll find the knee in the cost/benefit curve well below gzip-9. Also, if you're storing jpegs or video files, those are already compressed, in which case the benefit will zero even at gzip-9. That said, the other consideration is how you're using the storage. If the write rate is modest and disk space is at a premium, the CPU cost may simply not matter. And note that only writes are affected: when reading data back, gzip is equally fast regardless of level. Jeff _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
