zfs

No silent data corruption because of a checksum on each block, copy on write means no fsck EVER (it does not even have one), no RAID5 write hole, add disks to the pool on the fly, put volumes there as well as filesystems and export them via iSCSI or NFS »

I love the SunOS kernel. ZFS, Dtrace, Zones all make it desirable. But OpenSolaris is a code repository, not a distribution and you have to go elsewhere if you want a free distro. Nexenta looked the most promising, but then went quiet for a while (at »