SUMMARY OF MAJOR KNOWN PROBLEMS IN v0.4.0 (Development Release) - 'zpool create' hangs in the create ioctl() when initializing a new pool backed by loopback devices. The lo-raid0 configuration easily recreates this issue. I currently suspect a problem in vdev_disk.c implementation is causing this, but I have not yet looked to closely. On the surface things appear to be fine when creating the pool with real device or files. ./zpios.sh -c lo-raid0 -t tiny -v - SPLError: 10167:1968:(spl-kmem.c:1286:spl_kmem_cache_reap_now()) ASSERTION(skc->skc_magic == SKC_MAGIC) failed The above assertion is overserved when perform more IO than can be fully cached by the ARC. The Linux VM applies back pressure to the slab which in turn detect what appears to be memory corruption. I've seen a few flavors of this so far, so I'm not yet convinced this is actually an issue with the SPL slab. It may just be the most common victim, more investigation is needed. It is also possible the new untested vdev_disk.c is to blame. A lot of work is needed here. - SPLError: 7324:1224:(dnode.c:304:dnode_create()) VERIFY3(0` >= 1`) When enabling debugging in ZFS with the --enable-debug configure option we always trip the following VERIFY. This issue was present in the previous 0.3.3 release and was avoided simply by leaving debugging disabled until it could be explained. Well it has not just gone always with the update to b105 so we need to run it to ground and explain what is going on.