Red Hat Bugzilla – Bug 470216
EXT4-fs error (device xvda5): ext4_get_group_desc: block_group >= groups_count - block_group = 1, groups_count = 1
Last modified: 2009-01-10 11:25:35 EST
Created attachment 322687 [details] /etc/fstab Description of problem: The message in summary is observed in dmesg while system boots Version-Release number of selected component (if applicable): kernel-xen-2.6.18-121.el5 How reproducible: Not sure Steps to Reproduce: 1. Install PV xen guest on x86_64 with RHEL 5.3 snap #1 using the attached disk layout. 2. Boot the system 3. Actual results: error message when system boots Expected results: no error message Additional info: xvda5 is /home after doing touch /home/test as root the file is created but a message is printed on the console: JBD: barrier-based sync failed on xvda5 - disabling barriers
Created attachment 322688 [details] /var/log/dmesg
Created attachment 322689 [details] /var/log/messages
Well, I'm pretty sure our PV disk implementation doesn't support barriers (we had a long discussion about it a few months back). Are barriers required for EXT-4 to function? Also, is EXT-4 going to be supported in 5.3, or is still going to be tech preview? Chris Lalancette
ext4 will be tech preview in 5.3. Other questions I can't answer.
OK, then it shouldn't be a blocker for 5.3. We'll have to track down what else is going on here; if it turns out we do need barriers, that can be done, it will just have to be 5.4. Chris Lalancette
ext4 cannot require barriers, because LVM does not support barriers either. As for what the ext4 message means, maybe Eric Sandeen knows.
ext4 does not require barriers. JBD: barrier-based sync failed on xvda5 - disabling barriers is just telling you that they can't be used. It's also not the cause of this problem; barriers won't matter 'til you crash and have to replay the logs. FWIW it's a terribly confusing message. It should be more like: ext4_get_group_desc: block_group >= groups_count; block_group = 1, groups_count = 1 Anyway, fixed upstream by: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=565a9617b2151e21b22700e97a8b04e70e103153 and we'll likely be rebasin ext4 for 5.4 ... Is this a small, single-bg filesystem?
OK, so all the warning does is tell you the filesystem has only one block group. I'll drop this one from the kernel-xen bug list.
Rik, well, it does mark the fs with errors, which is somewhat problematic. But it's not a terribly big deal other than the "mounting filesystem with errors, fsck recommended" message. A single-bg filesystem is pretty rare too, I think. -Eric