Red Hat ENTERPRISE LINUX 4 - LVM ADMINISTRATOR Manual page 100

Appendix B. The LVM Configuration Files
# reconfigures a mirror as necessary. If no mirror library is
# provided, mirrors are not monitored through dmeventd.
# mirror_library = "libdevmapper-event-lvm2mirror.so"
# snapshot_library is the library used when monitoring a snapshot
device.
#
# "libdevmapper-event-lvm2snapshot.so" monitors the filling of
# snapshots and emits a warning through syslog, when the use of
# snapshot exceedes 80%. The warning is repeated when 85%, 90% and
# 95% of the snapshot are filled.
# snapshot_library = "libdevmapper-event-lvm2snapshot.so"
#}
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