Cameron Berkenpas posted on Tue, 17 Mar 2015 10:26:10 -0700 as excerpted: > I've figured out at least part of the issue. > > I had blk-mq enabled by default (SCSI_MQ_DEFAULT=y). I've since set > SCSI_MQ_DEFAULT=n, and now I'm completely stable with 4.0-rc4, 3.18.9, > and presumably all the others. This is on both the bcache and non-bcache > systems. > > All of my systems with btrfs and SCSI_MQ_DEFAULT=y are stable unless > they're using a 3ware 9750 controller (which I believe is the 3w-sas > driver from the top of my head). So either there's a bug with > blk-mq+3w-sas+btrfs, or just blk-mq+3w-sas. I suspect the latter, but if > I can find the time, I'll try to test with another filesystem. > > I suspect other controllers/drivers could be affected as well. > > Are any btrfs devs interested in me looking into this further? > > As a side note, in spite of all the crashes I've had through out my > testing etc, bcache+btrfs hasn't given me any issues like I've seen in > the past. This is just a few weeks worth of testing, but it seems > there's at least some sort of basic stability with bcache+btrfs now. Wow. Thanks! I'm not a dev so won't attempt to answer whether they have further interest or not, but thanks for keeping with this until you found the scsi-mq and 32-sas connection and reported it. It'll very possibly be of use to someone else later, and meanwhile, that's one less instability- mystery hanging over btrfs alone, now, which surely lets all regulars here rest easier. =:^) And that despite all the crashes during testing, bcache+btrfs didn't demonstrate any filesystem instabilities, demonstrates how far both of those components has come, each on its own and working together, as well. I know we get bcache+btrfs questions from time to time and the stability here even under repeated crashes triggered by unrelated factors is something I'm sure many will find reassuring. =:^) So thanks, again! =:^) -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- 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
