On Tue, Jan 17, 2012 at 06:02:32PM +0800, Miao Xie wrote: > So we'd better make the behaviour of chunk allocation correspond with space > reservation and free space allocation, if there is no enough disk space to > allocate RAID(RAID0, RAID1, RAID10) chunks, we degenerate the profile and try > to allocate chunks again. Otherwise, enospc will happen though we reserve > the space successfully and BUG_ON() will be triggered. > > Degenerating rule: > RAID10 -> RAID1 -> DUP > RAID0 -> SINGLE
I think that silently changing RAID level under unpredictable conditions could be a very unpleasant suprise to the administrator. Even worse when it requires manual intervention to undo the change and without any possibility to prevent it to happen again. In case ENOSPC happens early due to overbooking (like untarring lots of files as reported several times), will probably make it happen sooner than when "there is absolutely no free space available". We will lose automatic raid1-repair and scrub repair capabilities, that's not good. david -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
