llog_reader(8)

NAME
llog_reader - lustre on-disk log parsing utility

SYNOPSIS
llog_reader filename

DESCRIPTION
llog_reader parses the binary format of Lustre's on-disk configuration logs. It can only read the logs. Use tunefs.lustre to write to them.

To examine a log file on a stopped Lustre server, first mount its backing file system as ldiskfs, then use llog_reader to dump the log file's contents, e.g.

    mount -t ldiskfs /dev/sda /mnt/mgs
    llog_reader /mnt/mgs/CONFIGS/tfs-client

To examine the same log file on a running Lustre server, use the ldiskfs-enabled debugfs utility (called debug.ldiskfs on some distros) to extract the file, e.g.

    debugfs -c -R 'dump CONFIGS/tfs-client /tmp/tfs-client' /dev/sda
    llog_reader /tmp/tfs-client

To examine Changelog records on a stopped Lustre server, first mount its backing file system as ldiskfs, then use llog_reader to dump the log changelog's contents, e.g.

    # mount -t ldiskfs /dev/sda /mnt/mgs
    # llog_reader /mnt/mgs/changelog_catalog
    rec #1 type=1064553b len=64 offset 8192
    Header size : 8192
    Time : Mon Jan 22 23:28:24 2018
    Number of records: 1
    Target uuid :
    -----------------------
    #01 (064)id=[0x5:0x1:0x0]:0 path= O/1/d5/5 # llog_reader /mnt/mgs/ O/1/d5/5
    rec #1 type=10660000 len=136 offset 8192
    rec #2 type=10660000 len=136 offset 8328
    rec #3 type=10660000 len=128 offset 8464
    Header size : 8192
    Time : Mon Jan 22 23:30:01 2018
    Number of records: 3
    Target uuid :
    -----------------------
    #01 (136)changelog record id:0x0 cr_flags:0x9000 cr_type:CREAT(0x1)
    date:'14:30:01.370700741 2018.01.22' target:[0x200000402:0x1:0x0]
    cr_extra_flags:0x3 user:0:0 nid:10.128.11.159@tcp parent:[0x200000007:0x1:0x0]
    name:fileA

CAVEATS
Although they are stored in the CONFIGS directory, mountdata files do not use the config log format and will confuse llog_reader.

SEE ALSO
Lustre Operations Manual, Section 21.1, Troubleshooting Lustre.
lustre(7), tunefs.lustre(8)