Next3 - a word from the sponsor (Score 1)

It is a perfect timing to be asking this question. CTERA has just announced Next3 this week (http://lwn.net/Articles/391339/) and Next3 is available (for kernel 2.6). Next3 was designed for this exact purpose: providing Volume Shadow Copies over Ext3. Next3 snapshots are instantaneous and have small performance overhead. With CTERA NAS appliances, Windows clients can actually use the "Previous versions" button to view file history, just as easy as with a Windows file server. Next3 does not try to compete with Btrfs (or ZFS), it is but a complementary feature for Ext3, which people do seem to find missing and will hopefully be merged also into Ext4 some day.