Quoting Bernd Schubert (2013-05-23 08:55:47) > Hi all, > > we got a new test system here and I just also tested btrfs raid6 on > that. Write performance is slightly lower than hw-raid (LSI megasas) and > md-raid6, but it probably would be much better than any of these two, if > it wouldn't read all the during the writes. Is this a known issue? This > is with linux-3.9.2. Hi Bernd, Any time you do a write smaller than a full stripe, we'll have to do a read/modify/write cycle to satisfy it. This is true of md raid6 and the hw-raid as well, but their reads don't show up in vmstat (try iostat instead). So the bigger question is where are your small writes coming from. If they are metadata, you can use raid1 for the metadata. -chris -- 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
