man: dmeventd vdo plugin

1 files changed, 37 insertions, 2 deletions

diff --git a/man/dmeventd.8_main b/man/dmeventd.8_main
index 06f8f58c5..dc4abf627 100644
--- a/man/dmeventd.8_main
+++ b/man/dmeventd.8_main
@@ -125,6 +125,36 @@ To see the fullness of a thin pool command may check these
 two environmental variables
 \fBDMEVENTD_THIN_POOL_DATA\fP and \fBDMEVENTD_THIN_POOL_METADATA\fP.
 Command can also read status with tools like \fBlvs\fP(8).
+
+.HP
+.BR Vdo
+.br
+Monitors how full a VDO pool data is becoming and emits
+a warning to syslog when it exceeds 80% full.
+The warning is repeated when more then 85%, 90% and 95%
+of the VDO pool is filled. See
+.BR lvm.conf (5).
+When a VDO pool fills over 50% vdo plugin calls
+configured \fIdmeventd/vdo_command\fP with every 5% increase.
+With default setting it calls internal
+\fBlvm lvextend --use-policies\fP to resize VDO pool
+when it's been filled above the configured threshold
+\fIactivation/vdo_pool_autoextend_threshold\fP.
+If the command fails, dmeventd vdo plugin will keep
+retrying execution with increasing time delay between
+retries upto 42 minutes.
+User may also configure external command to support more advanced
+maintenance operations of a VDO pool.
+Such external command can e.g. remove some unneeded space
+with \fBfstrim\fP(8),
+but also can use \fBlvextend --use-policies\fP if other actions
+have not released enough space.
+Command is executed with environmental variable
+\fBLVM_RUN_BY_DMEVENTD=1\fP so any lvm2 command executed
+in this environment will not try to interact with dmeventd.
+To see the fullness of a VDO pool command may check this
+environmental variable \fBDMEVENTD_VDO_POOL\fP.
+Command can also read status with tools like \fBlvs\fP(8).
 .
 .SH ENVIRONMENT VARIABLES
 .
@@ -139,10 +169,15 @@ Variable is set by thin plugin and is available to executed program. Value prese
 actual usage of thin pool metadata volume. Variable is not set when error event
 is processed.
 .TP
+.B DMEVENTD_VDO_POOL
+Variable is set by vdo plugin and is available to executed program. Value present
+actual usage of VDO pool data volume. Variable is not set when error event
+is processed.
+.TP
 .B LVM_RUN_BY_DMEVENTD
-Variable is set by thin plugin to prohibit recursive interation
+Variable is set by thin and vdo plugin to prohibit recursive interation
 with dmeventd by any executed lvm2 command from
-a thin_command environment.
+a thin_command, vdo_command environment.
 .
 .SH SEE ALSO
 .