I just recently discovered something about btrfs filesystem balance that (as far as I can see) isn't documented anywhere, and doesn't necessarily have an obvious (to the average user) explanation. Apparently, trying to use -mconvert=dup or -sconvert=dup on a multi-device filesystem using one of the RAID profiles for metadata fails with a statement to look at the kernel log, which doesn't show anything at all about the failure. Based on what I've been able to understand from the source, it appears that the kernel stops you from converting to a dup profile for metadata in this case because it thinks that such a profile doesn't work on multiple devices, despite the fact that you can take a single device filesystem, and a device, and it will still work fine even without converting the metadata/system profiles. I feel at the very least, this should be documented, and the kernel should give at least some indication of what went wrong. Ideally, this should be changed to allow converting to dup so that when converting a multi-device filesystem to single-device, you never have to have metadata or system chunks use a single profile. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
