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NAME

       ZED - ZFS Event Daemon

SYNOPSIS

       zed [-d zedletdir] [-f] [-F] [-h] [-L] [-M] [-p pidfile] [-P path] [-s statefile] [-v] [-V] [-Z]

DESCRIPTION

       ZED  (ZFS Event Daemon) monitors events generated by the ZFS kernel module.  When a zevent (ZFS Event) is
       posted, ZED will run any ZEDLETs (ZFS Event Daemon Linkage for Executable Tasks) that have  been  enabled
       for the corresponding zevent class.

OPTIONS

       -h     Display a summary of the command-line options.

       -L     Display license information.

       -V     Display version information.

       -v     Be verbose.

       -f     Force  the daemon to run if at all possible, disabling security checks and throwing caution to the
              wind.  Not recommended for use in production.

       -F     Run the daemon in the foreground.

       -M     Lock all current and future pages in the virtual memory address space.  This may help  the  daemon
              remain responsive when the system is under heavy memory pressure.

       -Z     Zero the daemon's state, thereby allowing zevents still within the kernel to be reprocessed.

       -d zedletdir
              Read the enabled ZEDLETs from the specified directory.

       -p pidfile
              Write the daemon's process ID to the specified file.

       -P path
              Custom  $PATH  for  zedlets  to  use.   Normally  zedlets  run  in a locked-down environment, with
              hardcoded paths to the ZFS commands ($ZFS, $ZPOOL, $ZED, ...), and a  hardcoded  $PATH.   This  is
              done  for  security reasons.  However, the ZFS test suite uses a custom PATH for its ZFS commands,
              and passes it to zed with -P.  In short, -P is only to be used by the ZFS test suite; never use it
              in production!

       -s statefile
              Write the daemon's state to the specified file.

ZEVENTS

       A  zevent  is  comprised  of  a  list  of nvpairs (name/value pairs).  Each zevent contains an EID (Event
       IDentifier) that uniquely identifies it throughout the lifetime of the loaded ZFS kernel module; this EID
       is  a  monotonically  increasing  integer  that  resets to 1 each time the kernel module is loaded.  Each
       zevent also contains a class string that identifies the type of event.  For brevity, a subclass string is
       defined that omits the leading components of the class string.  Additional nvpairs exist to provide event
       details.

       The kernel maintains a list of recent zevents that can be viewed (along with their  associated  lists  of
       nvpairs) using the "zpool events -v" command.

CONFIGURATION

       ZEDLETs  to be invoked in response to zevents are located in the enabled-zedlets directory.  These can be
       symlinked or copied from the installed-zedlets directory; symlinks allow for automatic updates  from  the
       installed  ZEDLETs,  whereas copies preserve local modifications.  As a security measure, ZEDLETs must be
       owned by root.  They must have execute permissions for the user, but they must not have write permissions
       for group or other.  Dotfiles are ignored.

       ZEDLETs  are named after the zevent class for which they should be invoked.  In particular, a ZEDLET will
       be invoked for a given zevent if either its class or subclass string is a prefix of its filename (and  is
       followed  by  a  non-alphabetic  character).   As  a  special case, the prefix "all" matches all zevents.
       Multiple ZEDLETs may be invoked for a given zevent.

ZEDLETS

       ZEDLETs are executables invoked by the ZED in response to a given zevent.  They should be  written  under
       the  presumption  they can be invoked concurrently, and they should use appropriate locking to access any
       shared resources.  Common variables used by ZEDLETs can be stored in the default rc file which is sourced
       by scripts; these variables should be prefixed with "ZED_".

       The  zevent  nvpairs are passed to ZEDLETs as environment variables.  Each nvpair name is converted to an
       environment variable in the following manner: 1) it is prefixed with "ZEVENT_", 2)  it  is  converted  to
       uppercase,  and  3)  each  non-alphanumeric  character  is  converted  to an underscore.  Some additional
       environment variables have been defined to present certain nvpair values in a more convenient  form.   An
       incomplete list of zevent environment variables is as follows:

       ZEVENT_EID
              The Event IDentifier.

       ZEVENT_CLASS
              The zevent class string.

       ZEVENT_SUBCLASS
              The zevent subclass string.

       ZEVENT_TIME
              The time at which the zevent was posted as "seconds nanoseconds" since the Epoch.

       ZEVENT_TIME_SECS
              The seconds component of ZEVENT_TIME.

       ZEVENT_TIME_NSECS
              The nanoseconds component of ZEVENT_TIME.

       ZEVENT_TIME_STRING
              An almost-RFC3339-compliant string for ZEVENT_TIME.

       Additionally, the following ZED & ZFS variables are defined:

       ZED_PID
              The daemon's process ID.

       ZED_ZEDLET_DIR
              The daemon's current enabled-zedlets directory.

       ZFS_ALIAS
              The ZFS alias (name-version-release) string used to build the daemon.

       ZFS_VERSION
              The ZFS version used to build the daemon.

       ZFS_RELEASE
              The ZFS release used to build the daemon.

       ZEDLETs  may  need  to  call other ZFS commands.  The installation paths of the following executables are
       defined: ZDB, ZED, ZFS, ZINJECT, and ZPOOL.  These variables can be overridden in the rc file if needed.

FILES

       /etc/zfs/zed.d
              The default directory for enabled ZEDLETs.

       /etc/zfs/zed.d/zed.rc
              The default rc file for common variables used by ZEDLETs.

       /usr/lib/zfs-linux/zed.d
              The default directory for installed ZEDLETs.

       /var/run/zed.pid
              The default file containing the daemon's process ID.

       /var/run/zed.state
              The default file containing the daemon's state.

SIGNALS

       HUP    Reconfigure the daemon and rescan the directory for enabled ZEDLETs.

       TERM   Terminate the daemon.

NOTES

       ZED requires root privileges.

BUGS

       Events are processed synchronously by a single thread.  This can delay  the  processing  of  simultaneous
       zevents.

       There  is  no  maximum  timeout  for  ZEDLET execution.  Consequently, a misbehaving ZEDLET can delay the
       processing of subsequent zevents.

       The ownership and permissions of the enabled-zedlets directory (along with all  parent  directories)  are
       not  checked.   If  any  of  these directories are improperly owned or permissioned, an unprivileged user
       could insert a ZEDLET to be executed as root.  The requirement that ZEDLETs be owned  by  root  mitigates
       this to some extent.

       ZEDLETs are unable to return state/status information to the kernel.

       Some  zevent  nvpair  types  are not handled.  These are denoted by zevent environment variables having a
       "_NOT_IMPLEMENTED_" value.

       Internationalization support via gettext has not been added.

       The configuration file is not yet implemented.

       The diagnosis engine is not yet implemented.

LICENSE

       ZED (ZFS Event Daemon) is distributed under the terms of the Common Development and Distribution  License
       Version 1.0 (CDDL-1.0).

       Developed at Lawrence Livermore National Laboratory (LLNL-CODE-403049).

SEE ALSO

       zfs(8), zpool(8)