> On Feb 27, 2017, at 1:28 PM, Shaohua Li <shli@xxxxxxxxxx> wrote: > > On Mon, Feb 27, 2017 at 09:49:59AM -0500, Les Stroud wrote: >> After a period of a couple of weeks with one of our test instances having this problem every other day, they were all nice enough to operate without an issue for 9 days. It finally reoccurred last night on one of the machines. >> >> It exhibits the same symptoms and the call traces look as they did previously. This particular instance is configured with a deadline scheduler. I was able to capture the inflight you requested: >> >> $ cat /sys/block/xvd[abcde]/inflight >> 0 0 >> 0 0 >> 0 0 >> 0 0 >> 0 0 >> >> I’ve had this happen on instances with the deadline scheduler and the noop scheduler. At this point, I have not had this happen on an instance that is noop and the raid filesystem (ext4) is mounted with nobarrier. The instances with noop/nobarrier have not been running long enough for me to make any sort of conclusion that it works around the problem. Frankly, I’m not sure I understand the interaction between ext4 barriers and raid0 block flushes well enough to theorize whether it should or shouldn’t make a difference. > > If nobarrier, ext4 doesn't send flush request. So, could ext4’s flush request deadlock with an md_flush_request? Do they share a mutex of some sort? Could one of them be failing to acquire a mutex and not handling it? > >> Does any of this help with identifying the bug? Is there anymore information I can get that would be useful? > > > Unfortunately I can't find anything fishing. Does the xcdx disk correctly > handle flush request? For example, you can do the same test with a single such > disk and check if anything wrong. Until recently, we had a number of these systems setup without raid0. This issue never occurred on those systems. Unfortunately, I can’t find a way to make it happen other than stand a server up and let it run. I suppose I could try a different filesystem and see if that makes a difference (maybe ext3, xfs, etc). > > Thanks, > Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
