Fujitsu ETERNUS Multipath Driver V2, Руководство пользователя

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Chapter 3 Multipath Driver Functions and Operation
3.1 Path Management
FUJITSU Storage ETERNUS Multipath Driver V2 User’s Guide for Linux
Copyright 2014 FUJITSU LIMITED P2U3-0031-15ENZ0
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(1) initialization

active/standby
The Multipath Driver automatically configures the path connections at system startup.
Paths connected to assigned CMs are automatically set to active.
Paths connected to non-assigned CMs are set to standby.
(2) standby

active
When an error in an active path is detected during I/O, or the path status changes from active to stop, the
standby path becomes the active path if no other active path is available.
When the path connected to the assigned CM is recovered and becomes the active path again, the
activated standby path connected to the non-assigned CM returns to standby.
(3) active/standby

warning
When a path error occurs during a normal I/O process or upon checking, the active/standby path status
changes to warning.
When the path is re-enabled by path checking, the path status returns to active/standby.
(4) warning

fail
When judged as unusable as a result of the warning period checking, path status changes to fail.
When the check result is normal for a failed path, its status changes to warning.
(5) warning

fatal fail
When the status stays in warning for a long period of time, or when the status frequently changes between
active/standby and warning, it is determined that appropriate checks cannot be performed and the status
changes to fatal fail, in which the target is not checked.
(6) fatal fail

active/standby
When a failed path is re-enabled by the "iompadm restart" command, the path status changes back to
active/standby.
When the status frequently changes between active/standby and warning, it is determined that
appropriate checks cannot be performed and the status changes to fatal fail, in which the target is not
checked.
(7) active/standby

stop
When the path is disconnected by the "iompadm change" command, the path status changes to stop.
When the path is re-enabled by the "iompadm restart" command, the path status changes to active/
standby.
(8) active/standby

fail
When a serious failure is detected in the ordinary I/O process or active/standby check, the path status
changes to fail.
When the path is re-enabled by the "iompadm restart" command, the path status changes to active/
standby.
When the path status changes, the path connected to the assigned CM becomes active, and the path
connected to the non-assigned CM becomes standby. However, if there are no active paths connected to the
assigned CM, the path connected to the non-assigned CM will become active.
For SAS connection, the operating path information will disappear (not be displayed in the result of the
"iompadm info" command) for "Link Down" paths. This path information will reappear when the link is
restored.