On Mon, 2010-05-03 at 22:02 +0200, Roy Sigurd Karlsbakk wrote: > Is raid[56] coming to btrfs? There was some talk about it a year back > or so, but I haven't seen anything yet.... Um, there was some talk about it about four days ago. You even participated in that thread! As it stands, it has the traditional 'write hole' problem -- when you overwrite _part_ of a stripe, you have to update the parity block(s) too and you have a short period of time where the parity doesn't match the actual data. If you get a crash followed by a disk failure during that period of time, you get data loss. The solution is always to write a full stripe (across all the disks in the set). Chris said he'd sort that out in the upper layers of btrfs, about which I know little. We've been waiting a while for that. I poked him recently and we realised that I hadn't actually made my part _cope_ with being given a full stripe at a time, which was a bit of an oversight. I had done it once as a test, but had never actually committed and pushed that support. The patch I posted last week attempts to fix that. There are one or two details I wanted some feedback on but in the absence of that, I think I'll just tidy it up and push it using the existing approach. -- dwmw2 -- 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
