Public bug reported: We upgraded our 12.04 LTS on 9 July at around 18:30. Immediately after the reboot, the I/O on the / partition (sda) was extremely high. This was causing sluggish responsiveness on the NFS server who's exported directory is on a different file system (sdb) and LUN (disk).
I investigated the problem and found using iotop that the process "jbd2/sda2-8" was responsible for an extremely high number of I/O operations Total DISK READ: 0.00 B/s | Total DISK WRITE: 13.33 M/ TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND 293 be/3 root 0.00 B/s 0.00 B/s 0.00 % 39.16 % [jbd2/sda2-8] I turned on file system debugging using echo 1 > /sys/kernel/debug/tracing/events/ext4/ext4_sync_file_enter/enable echo 1 >/sys/kernel/debug/tracing/events/jbd2/jbd2_run_stats/enable and found that one inode was being massively addressed. jbd2/sda2-8-293 [000] 260587.952474: jbd2_run_stats: dev 8,2 tid 42050430 wait 0 running 0 locked 0 flushing 0 logging 0 handle_count 2 blocks 7 blocks_logged 8 nfsd-1332 [000] 260587.953142: ext4_sync_file_enter: dev 8,2 ino 150 parent 16987 datasync 0 This inode (150) belongs to /var/lib/nfs/v4recovery Further investigation showed in dmesg that shortly after booting the directory /var/lib/nfs/v4recovery couldn't be written to: [ 99.020861] NFSD: failed to write recovery record (err -17); please check that /var/lib/nfs/v4recovery exists and is writeable [ 99.089156] NFSD: failed to write recovery record (err -17); please check that /var/lib/nfs/v4recovery exists and is writeable [ 99.189010] NFSD: failed to write recovery record (err -17); please check that /var/lib/nfs/v4recovery exists and is writeable I have tried deleting and recreating the directory /var/lib/nfs/v4recovery with 777 permissions however this did not solve the problem. These messages were still produced even after a reboot. The I/O operations per second are sometimes in excess of 1000 and typically around 500-750. This is completely different behaviour to the previous kernel where the I/O operations were in the 5-20 I/O operations per second with peaks around 30. I will attach a graph from our central EMC storage system of the LUN for a graphical view of before and after the update. There were no changes in the parameters or shares to the NFS server and I have not been able to find any documentation about parameters that we should change to address such a problem so I can only conclude with this behaviour that this is a bug of some decsription. Additional information about our system: $ uname -a Linux wsps428 3.2.0-87-generic #125-Ubuntu SMP Fri Jun 19 08:25:10 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux $ cat /proc/version_signature Ubuntu 3.2.0-87.125-generic 3.2.69 $ lsb_release -rd Description: Ubuntu 12.04.5 LTS Release: 12.04 $ apt-cache policy nfs-server nfs-server: Installed: (none) Candidate: (none) Version table: I will attach a dmesg output. ** Affects: ubuntu Importance: Undecided Status: New ** Attachment added: "dmesg.out" https://bugs.launchpad.net/bugs/1473948/+attachment/4428262/+files/dmesg.out -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1473948 Title: After most recent upgrade to 3.2.0-87-generic, nfs server process has extremely high I/O to /var/lib/nfs/v4recovery To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1473948/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs