According to recent information from Red Hat's Jeff Darcy on CloudFS (now known as HekaFS, following a trademark dispute over the cloud name), setup of XtreemFS is quite easy, but replication is a bit difficult. Beyond a few hurdles, "XtreemFS was the only distributed filesystem besides GlusterFS that could get through my “smoke test” without crashes, hangs, or data corruption."
Jeff concludes, "That might not seem like a very high standard considering that the test is just iozone reading and writing files sequentially, but four out of six distributed filesystems that I’ve tested (or tried to test) couldn’t even get that far. I wasn’t testing on systems where performance results would be really meaningful except to say that I test GlusterFS this way all the time and XtreemFS performance didn’t seem radically different. The fact that XtreemFS can handle even that much, along with the relative ease of installation and setup, already puts it at #2 on my list. I expect that when 1.3 does come out it will address at least some of the issues I’ve mentioned and offer a worthwhile choice for those who are interested in its unique feature set. I highly recommend that anyone interested in this area give it a look."
More information on the XtreemFS cloud file-system project is available from XtreemFS.org.