[LU-3446] changelog index reset on MDT restart

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.4.1, Lustre 2.5.0
• Affects Version/s: Lustre 2.4.0
• Labels: HB changelog
• Environment: mds: lustre-2.4.0-RC2_2chaos_2.6.32_358.6.1.3chaos.ch5.1.ch5.1.x86_64
• Severity: 3
• Assignee: Zhenyu Xu
• Reporter: Ned Bass (Inactive)

Description

After a maintenance downtime in which we updated our vesta Lustre servers from 2.4.0-RC1_3chaos to 2.4.0-RC2_2chaos, the changelog current index reverted to zero. The registered user cl1 retained its highest index value:

# vesta-mds1 /root > lctl get_param mdd.fsv MDT0000.changelog_users                                                                     
mdd.fsv-MDT0000.changelog_users=
current index: 9158128
ID    index
cl1   445461827

Here is a debug log entry from when the MDS started:

00000004:00000080:1.0:1370534969.929148:0:17901:0:(mdd_device.c:308:mdd_changelog_llog_init()) changelog starting index=0

LLNL-bug-id: TOSS-2103