> On 04/17/2013 02:09 PM, Stefan Priebe wrote: >> >> Sorry to disturb, but what is the raeson / advantage of using zfs for >> ceph? A few things off the top of my head: 1) Very mature filesystem with full xattr support (this bug notwithstanding) and copy-on-write snapshots. While the port to Linux sometimes has some rough edges (but in my experience over the past few years is generally very good), the main code from Solaris (and now the Illumos project) is well-tested and very well regarded. Btrfs has many of the same features, but in my real-world experience I've had multiple btrfs filesystems go corrupt with very innocuous usage patterns and across a variety of kernel versions. The zfsonlinux bugs don't tend to be data-destructive, once data is written to it. 2) Very intelligent caching; also supports external devices (like SSDs) for a level 2 cache. This speeds up reads dramatically. 3) Very robust error-checking. There are lots of stories of ZFS finding bad memory, bad controllers, and bad hard drives because of its checksumming (which you can optionally turn off for speed). If you set up the OSDs such that each OSD is based off of a ZFS mirror, you get these benefits locally. For some people, especially when heavy on reads (due to the intelligent caching), a solution that knocks the remote replication level down by one but uses local mirrors for OSDs may provide good functionality and safety compromises. --Jeff -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
