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  1. Lustre
  2. LU-15517

MDT stuck in recovery if one other MDT is failed over to partner node



    • Bug
    • Resolution: Unresolved
    • Critical
    • None
    • Lustre 2.12.8
    • 3.10.0-1160.53.1.1chaos.ch6.x86_64
    • 3
    • 9223372036854775807


      MDT fails to enter recovery when there is one MDT running on its partner MDS. The recovery_status file indicates "WAITING" and reports the MDT running on its parter as a non-ready MDT.

      The console log of the MDT unable to enter recovery repeatedly shows messages like:

      [Thu Feb  3 12:15:18 2022] Lustre: 4102:0:(ldlm_lib.c:1827:extend_recovery_timer()) lquake-MDT0009: extended recovery timer reached hard limit: 900, extend: 1
      [Thu Feb  3 12:15:18 2022] Lustre: 4102:0:(ldlm_lib.c:1827:extend_recovery_timer()) Skipped 29 previous similar messages

      My steps to reproduce:
      1. Start all MDTs on their primary MDS (in my case, that's jet1...jet16 => MDT0000...MDT000f). Allow them to complete recovery.
      2. umount MDT000e on jet15, and mount it on jet16. Allow it to complete recovery.
      3. umount MDT0009 on jet10, and then mount it again (on the same node, jet10, where it was happily running moments ago).

      Debug log shows that the update log for MDT000e was not received. There are no messages in the console log regarding MDT000e after MDT0009 starts up.

      I determined the PID of the thread lod_sub_recovery_thread() for MDT000e. The debug log shows the thread starts up, follows roughly this sequence of calls, and never returns from ptlrpc_set_wait().

      lod_sub_prep_llog>llog_osd_get_cat_list->dt_locate_at->lu_object_find_at-> ?->

      So apparently the RPC never times out, so upper layers never get to retry, there are no error messages reporting the problem, and the MDT never enters recovery.

      Our patch stack is:

      82ea54e (tag: 2.12.8_6.llnl) LU-13356 client: don't use OBD_CONNECT_MNE_SWAB
      d06f5b2 LU-15357 mdd: fix changelog context leak
      543b60b LU-9964 llite: prevent mulitple group locks
      d776b67 LU-15234 lnet: Race on discovery queue
      77040da Revert "LU-15234 lnet: Race on discovery queue"
      bba827c LU-15234 lnet: Race on discovery queue
      7faa872 LU-14865 utils: llog_reader.c printf type mismatch
      5dc104e LU-13946 build: OpenZFS 2.0 compatibility
      0fef268 TOSS-4917 grant: chatty warning in tgt_grant_incoming
      5b70822 TOSS-4917 grant: improve debug for grant calcs
      8af02e8 log lfs setstripe paths to syslog
      391be81 Don't install lustre init script on systemd systems
      c613926 LLNL build customizations
      a4f71cd TOSS-4431 build: build ldiskfs only for x86_64
      067cb55 (tag: v2_12_8, tag: 2.12.8) New release 2.12.8

      See https://github.com/LLNL/lustre/tree/2.12.8-llnl for the details.


        1. dk.1.jet16.txt.gz
          287 kB
        2. dk.3.txt.gz
          5.18 MB
        3. dmesg.jet16.txt.gz
          26 kB
        4. dmesg.txt.gz
          27 kB
        5. lu-15517.llog_reader.out
          328 kB



            tappro Mikhail Pershin
            ofaaland Olaf Faaland
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