Modifying Link Loss Behavior; Fibre Channel - Red Hat ENTERPRISE LINUX - ONLINE STORAGE RECONFIGURATION GUIDE BETA Configuration Manual

7. Modifying Link Loss Behavior

This section describes how to modify the link loss behavior of devices that use either fibre
channel or iSCSI protocols.

7.1. Fibre Channel

If a driver implements the Transport
through a link will be blocked when a transport problem is detected. To verify if a device is
blocked, run the following command:
cat /sys/block/<device>/device/state
This command will return
this command will return
Procedure 2. Determining The State of a Remote Port
1. To determine the state of a remote port, run the following command:
cat /sys/class/rport/rport-H:B:R/port_state
2. This command will return
through it) are blocked. If the remote port is operating normally, the command will return
.
Online
3. If the problem is not resolved within
unblocked and all IO running on that device (along with any new IO sent to that device) will
be failed.
Procedure 3. Changing
• To change the
dev_loss_tmo
set
dev_loss_tmo
echo 30 > /sys/class/rport/rport-H:B:R/dev_loss_tmo
For more information about
When a device is blocked, the fibre channel class will leave the device as is; i.e.
remain . This is because the
/dev/sdx
later time, the SCSI device will be used again.
dev_loss_tmo
if the device is blocked. If the device is operating normally,
blocked
.
running
when the remote port (along with devices accessed
Blocked
dev_loss_tmo
dev_loss_tmo
value,
echo
to 30 seconds, run:
, refer to
dev_loss_tmo
dev_loss_tmo
callback, access attempts to a device
seconds, the rport and devices will be
in the desired value to the file. For example, to
Section 2.1, "Fibre Channel
expired. If the link problem is fixed at a
Fibre Channel
API".
will
/dev/sdx
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