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home | helpx minix x x minixx DMEVENTD(8) System Manager's Manual DMEVENTD(8) NAME dmeventd -- Device-mapper event daemon SYNOPSIS dmeventd [-d [-d [-d]]] [-f] [-h] [-l] [-R] [-V] [-?] DESCRIPTION dmeventd is the event monitoring daemon for device-mapper devices. Li- brary plugins can register and carry out actions triggered when partic- ular events occur. OPTIONS -d Repeat from 1 to 3 times ( -d, -dd, -ddd ) to increase the de- tail of debug messages sent to syslog. Each extra d adds more debugging information. -f Don't fork, run in the foreground. -h Show help information. -l Log through stdout and stderr instead of syslog. This option works only with option -f, otherwise it is ignored. -? Show help information on stderr. -R Replace a running dmeventd instance. The running dmeventd must be version 2.02.77 or newer. The new dmeventd instance will ob- tain a list of devices and events to monitor from the currently running daemon. -V Show version of dmeventd. LVM PLUGINS Mirror Attempts to handle device failure automatically. See lvm.conf(5). Raid Attempts to handle device failure automatically. See lvm.conf(5). Snapshot Monitors how full a snapshot is becoming and emits a warning to syslog when it exceeds 80% full. The warning is repeated when 85%, 90% and 95% of the snapshot is filled. See lvm.conf(5). Snapshot which runs out of space gets invalid and when it is mounted, it gets umounted if possible. Thin Monitors how full a thin pool data and metadata 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 thin pool is filled. See lvm.conf(5). When a thin pool fills over 50% (data or metadata) thin plugin calls configured dmeventd/thin_command with every 5% increase. With default setting it calls internal lvm lvextend --use-policies to resize thin pool when it's been filled above configured threshold activation/thin_pool_autoex- tend_threshold. If the command fails, dmeventd thin plugin will keep retrying execution with increasing time delay between re- tries upto 42 minutes. User may also configure external command to support more advanced maintenance operations of a thin pool. Such external command can e.g. remove some unneeded snapshots, use fstrim(8) to free recover space in a thin pool, but also can use lvextend --use-policies if other actions have not released enough space. Command is executed with environmental variable LVM_RUN_BY_DMEVENTD=1 so any lvm2 command executed in this envi- ronment will not try to interact with dmeventd. To see the fullness of a thin pool command may check these two environmen- tal variables DMEVENTD_THIN_POOL_DATA and DMEVENTD_THIN_POOL_METADATA. Command can also read status with tools like lvs(8). Vdo Monitors how full a VDO pool data is becoming and emits a warn- ing 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 lvm.conf(5). When a VDO pool fills over 50% vdo plugin calls configured dmeventd/vdo_command with every 5% increase. With default setting it calls internal lvm lvextend --use-policies to resize VDO pool when it's been filled above the configured threshold activation/vdo_pool_autoextend_threshold. If the com- mand 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 ad- vanced maintenance operations of a VDO pool. Such external com- mand can e.g. remove some unneeded space with fstrim(8), but also can use lvextend --use-policies if other actions have not released enough space. Command is executed with environmental variable LVM_RUN_BY_DMEVENTD=1 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 DMEVENTD_VDO_POOL. Command can also read status with tools like lvs(8). ENVIRONMENT VARIABLES DMEVENTD_THIN_POOL_DATA Variable is set by thin plugin and is available to executed pro- gram. Value present actual usage of thin pool data volume. Vari- able is not set when error event is processed. DMEVENTD_THIN_POOL_METADATA Variable is set by thin plugin and is available to executed pro- gram. Value present actual usage of thin pool metadata volume. Variable is not set when error event is processed. DMEVENTD_VDO_POOL Variable is set by vdo plugin and is available to executed pro- gram. Value present actual usage of VDO pool data volume. Vari- able is not set when error event is processed. LVM_RUN_BY_DMEVENTD Variable is set by thin and vdo plugin to prohibit recursive in- teration with dmeventd by any executed lvm2 command from a thin_command, vdo_command environment. SEE ALSO lvm(8), lvm.conf(5) Red Hat Inc DM TOOLS 2.03.07(2) (2019-11-30) DMEVENTD(8)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | LVM PLUGINS | ENVIRONMENT VARIABLES | SEE ALSO