Fast_Io_Fail_Tmo Changing By Device Mapper Multipath - Hitachi GVX-CC64G*BX User Manual

fast_io_fail_tmo changing by Device
mapper multipath
When you use Device mapper multipath in SLES11, Device mapper multipath may update
the value of fast_io_fail_tmo automatically after OS starting.
When the value is set except "off" to fast_io_fail_tmo, instead of dev_loss_tmo, the value
of fast_io_fail_tmo is used on OS as "waiting time which waits for linkup in order that the
driver tries resending of the SCSI command after link down occurred".
When the value is set except "off" to fast_io_fail_tmo, please confirm a setup and operation
of Device mapper multipath.
The configuration file of Device mapper multipath is /etc/multipath.conf.
The value of fast_io_fail_tmo may be updated by default operation of Device mapper
multipath even if it is a case where /etc/multipath.conf does not exist.
[Function] Display of fast_io_fail_tmo
[Syntax]
<Display> cat /sys/class/fc_remote_ports/rport-xxxx/fast_io_fail_tmo
Since fast_io_fail_tmo exists for every SCSI target, the character string "xxxx" varies
depending on SCSI target ID.
Please display the fast_io_fail_tmo parameter of each SCSI target to check link down time
to two or more SCSI targets.
[Function] Setup of fast_io_fail_tmo
[Syntax]
<Setup> echo <setup value> > /sys/class/fc_remote_ports/rport-xxxx/fast_io_fail_tmo
Since fast_io_fail_tmo exists for every SCSI target, the character string "xxxx" varies
depending on SCSI target ID.
Please set the fast_io_fail_tmo parameter of each SCSI target to set up fast_io_fail to two
or more SCSI targets.
The value set up by this method has a case rewritten by other software than a driver
(example: Device mapper multipath).
Example: By changing the configuration file (/etc/multipath.conf) of Device mapper
multipath, it is possible to change the value set as fast_io_fail_tmo.
For details, please refer to the manual of Device mapper multipath.
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