From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from neo-zeon.de ([173.228.7.145]:32961 "EHLO neo-zeon.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753688AbbCFUDr (ORCPT ); Fri, 6 Mar 2015 15:03:47 -0500 Message-ID: <54FA081A.8010501@neo-zeon.de> Date: Fri, 06 Mar 2015 12:03:38 -0800 From: Cameron Berkenpas MIME-Version: 1.0 To: bo.li.liu@oracle.com CC: linux-btrfs@vger.kernel.org Subject: Re: System crash while scrubbing on 3.18.x References: <54F9005D.5070107@neo-zeon.de> <20150306123054.GB18885@localhost.localdomain> In-Reply-To: <20150306123054.GB18885@localhost.localdomain> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hello, I should have mentioned this earlier. I get absolutely nothing in the logs. I can't look at dmesg either as the system is completely unresponsive. On 03/06/2015 04:30 AM, Liu Bo wrote: > On Thu, Mar 05, 2015 at 05:18:21PM -0800, Cameron Berkenpas wrote: >> Hello, >> >> Sorry for the long email... >> >> I've found my system locks up when scrubbing with 3.18.x, but not >> with 3.17.8 across 2 systems. >> >> I have the following BTRFS partitions on system 1: >> / (128GiB, 49GiB used on SSD) >> /home (4.2TiB, 624GB used on HDD RAID volume) >> >> I have the following BTRFS partitions on system 2: >> / (196GiB, 17GiB used on HDD RAID volume) >> /home (7.1TiB, 2.9TiB used on HDD RAID volume) >> >> My OS is Netrunner 15 (which 98% Kubuntu) on system 1, and >> up-to-date debian testing on system 2. >> >> I've never encountered a lock up while scrubbing /. Just with /home. >> >> The systems never lock up immediately, but takes some time. VERY >> rarely I'll see the lockup when the scrub is at <100GiB completed. >> Typically it happens somewhere between 200-350GiB. A few times it's >> gone beyond 500GiB. This is probably why I've never encountered the >> issue with /, it's just not big enough on either system. >> >> Both systems were otherwise idle while performing the scrubs that >> crashed the systems. >> >> /home is on a partition on a RAID10 volume on a 3ware 9740-4i >> controller with 4x 3TB disks on system 1. On system 2, it's the same >> controller but with 4x 4TB disks (and / on system 2 is a partition >> on the same RAID volume rather than a separate disk). Both systems >> have 32GiB memory, and the otherwise the hardware is pretty >> different between the systems (AMD Vs. Intel, etc). >> >> I suspect that the RAID controller probably isn't relevant. Both >> arrays and their drives are healthy. >> >> I've also encountered the issue on a freshly formatted filesystem >> with my data copied from a backup on system 1. >> >> I've tried tried scrubbing with btrfs-progs 3.17 (installed from the >> distribution repos on both systems), and btrfs-progs from git (using >> tag v3.18.x). Neither version made a difference. >> >> In case this is helpful to anyone, here's how I've discovered the issue: >> I decided to test btrfs with bcache on system 1 to see if the >> stability had improved since I'd tried bcache+btrfs about a year >> ago. I backed up /home on system 1 and then freshly formatted it and >> set it to use bcache. I was running Linux 3.18.8 and encountered the >> problem that I've described above. I assumed the bcache+btrfs >> combination was still broken so I formatted the system again (this >> time still using btrfs, but without bcache) and copied all my files >> back. I encountered the same issue without bcache. Realizing the >> issue wasn't bcache related, I did ANOTHER format, this time back to >> bcache+btrfs. >> >> From here in my testing, I found that system 2 (which has no bcache) >> also crashed when scrubbing with Linux 3.18.8. I decided to try >> 3.17.8 on system 1 (since 3.18.8 seemed to be the common denominator >> between the 2 systems), found that fixed the issue, and then >> downgraded system 2 to use 3.17.8 as well, which also fixed the >> issue there. >> >> (Note: At one point I also tried Linux 3.18.7 and 3.18.5, however, >> those kernels are affected by the scrub/crash issue as well.) >> >> I found something else interesting when I tested against Linux >> 3.19.0. With 3.19.0, the bcache system always crashes fairly early >> in the scrub (<100GiB), but the non-bcache system has no issues. >> This suggests my problem with 3.19.0 is a bcache+btrfs issue (or >> simply an issue with bcache). >> >> I'm not sure if bcache is relevant to the BTRFS devs at this point, >> but I thought I'd put that there for anyone who might find that >> information useful. >> >> To summarize: >> I've tested with 2 systems, and scrubbing caused crashes occurred on >> both with Linux 3.18.8, but not with 3.17.8 for both systems >> I've tested 1 system with and without bcache, and bcache made no >> difference between Linux 3.17.8 and 3.18.8. >> I've tested with 3.19.0, and I crash when scrubbing on the bcache >> system, but not the non-bcache system. > Better to have some stacks about the scrub crash. > > Thanks, > > -liubo > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html