diff options
Diffstat (limited to 'sys/contrib/openzfs/man/man8/zed.8.in')
| -rw-r--r-- | sys/contrib/openzfs/man/man8/zed.8.in | 34 |
1 files changed, 33 insertions, 1 deletions
diff --git a/sys/contrib/openzfs/man/man8/zed.8.in b/sys/contrib/openzfs/man/man8/zed.8.in index c90a1834403b..2d19f2d8496b 100644 --- a/sys/contrib/openzfs/man/man8/zed.8.in +++ b/sys/contrib/openzfs/man/man8/zed.8.in @@ -13,7 +13,7 @@ .\" .\" Developed at Lawrence Livermore National Laboratory (LLNL-CODE-403049) .\" -.Dd May 26, 2021 +.Dd August 22, 2022 .Dt ZED 8 .Os . @@ -158,6 +158,8 @@ Multiple ZEDLETs may be invoked for a given zevent. 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. +The one exception to this are "synchronous zedlets", which are described later +in this page. Common variables used by ZEDLETs can be stored in the default rc file which is sourced by scripts; these variables should be prefixed with .Sy ZED_ . @@ -233,6 +235,36 @@ and .Sy ZPOOL . These variables may be overridden in the rc file. . +.Sh Synchronous ZEDLETS +ZED's normal behavior is to spawn off zedlets in parallel and ignore their +completion order. +This means that ZED can potentially +have zedlets for event ID number 2 starting before zedlets for event ID number +1 have finished. +Most of the time this is fine, and it actually helps when the system is getting +hammered with hundreds of events. +.Pp +However, there are times when you want your zedlets to be executed in sequence +with the event ID. +That is where synchronous zedlets come in. +.Pp +ZED will wait for all previously spawned zedlets to finish before running +a synchronous zedlet. +Synchronous zedlets are guaranteed to be the only +zedlet running. +No other zedlets may run in parallel with a synchronous zedlet. +Users should be careful to only use synchronous zedlets when needed, since +they decrease parallelism. +.Pp +To make a zedlet synchronous, simply add a "-sync-" immediately following the +event name in the zedlet's file name: +.Pp +.Sy EVENT_NAME-sync-ZEDLETNAME.sh +.Pp +For example, if you wanted a synchronous statechange script: +.Pp +.Sy statechange-sync-myzedlet.sh +. .Sh FILES .Bl -tag -width "-c" .It Pa @sysconfdir@/zfs/zed.d |