> Hello Marc, > > Sunday, July 29, 2007, 9:57:13 PM, you wrote: > > MB> MC <rac <at> eastlink.ca> writes: > >> > >> Obviously 7zip is far more CPU-intensive than > anything in use with ZFS > >> today. But maybe with all these processor cores > coming down the road, > >> a high-end compression system is just the thing > for ZFS to use. > > MB> I am not sure you realize the scale of things > here. Assuming the worst case: > MB> that lzjb (default ZFS compression algorithm) > performs as bad as lha in [1], > MB> 7zip would compress your data only 20-30% better > at the cost of being 4x-5x > MB> slower ! > > MB> Also, in most cases, the bottleneck in data > compression is the CPU, so > MB> switching to 7zip would reduce the I/O throughput > by about 4x. > > 1. it depends on a specific case - sometimes it's cpu > sometimes not > > 2. sometimes you don't really care about cpu - you > have hundreds TBs > of data rarely used and then squeezing 20-30% more > space is a huge > benefit - especially when you only read those files > once they are > written
* disks are probably cheaper than CPUs * it looks to me like 7z may also be RAM-hungry; and there are probably better ways to use the RAM, too No doubt it's an option that would serve _someone_ well despite its shortcomings. But are there enough such someones to make it worthwhile? This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
