Home > Storage > Data Storage Essentials > Storage Admin > Fabric Notifications with Dell PowerMax > PowerPath
Fabric Notifications support for PowerPath is available with PowerPath for Linux 7.4 and above. Currently, PowerPath only acts on link integrity events. Other events such as congestion are only logged at this time. PowerPath uses an aging period (default of 1 day) for clearing an event. After the aging period, PowerPath resets the path as active and the corresponding path (if healthy) will again be used for I/O.
Fabric Notifications are enabled by default with PowerPath. Below are the commands to disable and enable Fabric Notifications:
powermt set autostandby=off trigger=fpin //Disable
powermt set autostandby=on trigger=fpin //Enable
Below are other useful powermt CLIs:
CLI:
powermt display dev=<> Shows if a path is marked as asb:fpin.
powermt display options Shows FPIN aging period
Sample output:
[root@hostname ~]# powermt display options
Show CLARiiON LUN names: true
New lun probe interval: 120
Path Latency Monitor: Off
Performance Monitor: disabled
Autostandby: I/Os per Failure (iopf): enabled
IOPF aging period : 1 d
IOPF limit : 1000
FPIN notification : enabled
FPIN aging period : 1 d
When a link integrity notification is received, PowerPath marks the affected path as asb:fpin. PowerPath will not use the affected path for I/O unless all other active paths are unavailable. Autostandby (often abbreviated as Asb) specifies a path that has been placed into standby automatically using the proximity autostandby algorithm (asb:prox), the I/OsPerFailure-based autostandby algorithm (asb:iopf) or when a link integrity notification is received (asb:fpin). When a path is placed in autostandby mode through the Fabric Notifications trigger, PowerPath will add the aging amount to the current time. If Fabric Notifications are not received during this time, the aging period will timeout allowing PowerPath to return the paths for full use without user intervention. If any other Link Integrity Fabric Notifications are received, the aging period starts again from the time the paths are set to asb:fpin. Each path ages separately. This may result in each path having different times at which they return to their previous mode (active/standby). Below is the agingperiod command syntax and additional info:
agingperiod=<#days>|<#hours>h|<#hours>H
It specifies the number of days or hours after which a path in autostandby mode due to intermittent path failure or fpin automatically resets to active mode. Appending the number with h or H indicates the unit to be in hours. Otherwise it is considered to be in days. The default value is 1 day. The range of acceptable values is 0 to 24854 days or 0 to (24*24854) hours. There is no output displayed if success.Specifying 0 turns off the periodic reset of a path in autostandby due to intermittent path failure. These paths in autostandby (asb:iopf) or (asb:fpin) never return to active mode without manual intervention.
Please note that the asb path mode settings do not persist across reboots. For more information on PowerPath’s Fabric Notifications support, see the PowerPath Family for Linux and Minor Releases Release Notes and the powermt man pages.