On Tue, Aug 01, 2017 at 10:25:47PM +0500, Roman Mamedov wrote: > On Tue, 1 Aug 2017 10:14:23 -0600 > Liu Bo <bo.li....@oracle.com> wrote: > > > This aims to fix write hole issue on btrfs raid5/6 setup by adding a > > separate disk as a journal (aka raid5/6 log), so that after unclean > > shutdown we can make sure data and parity are consistent on the raid > > array by replaying the journal. > > Could it be possible to designate areas on the in-array devices to be used as > journal? > > While md doesn't have much spare room in its metadata for extraneous things > like this, Btrfs could use almost as much as it wants to, adding to size of > the > FS metadata areas. Reliability-wise, the log could be stored as RAID1 chunks. >
Yes, it makes sense, we could definitely do that, that was actually the original idea. I started with adding a new device for log as it looks easier to me, but I could try that now. > It doesn't seem convenient to need having an additional storage device around > just for the log, and also needing to maintain its fault tolerance yourself > (so > the log device would better be on a mirror, such as mdadm RAID1? more expense > and maintenance complexity). > That's true. Thanks for the suggestions. Thanks, -liubo -- 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
