Product manual

VTrak E-Class Product Manual
402
Linux MPIO: Known Issues
With a Fibre Channel switch, a dev_loss_tmo value set too small can result in
loss of the path during failover/failback.
Linux maintains the rports dev_loss_tmo value in the /sys/class/
fc_remote_port/rport-xxxx/dev_loss_tmo file. The Fibre Channel HBA driver
sets this value at loading time.
To change the dev_loss_tmo value to the recommended 60 seconds, during
runtime type the echo command:
echo 60 > /sys/class/fc_remote_port/rpot-1:0:0/dev_loss_tmo
Issue OS Description
1 SLES 11
GMC
OS multipath with SAS interface makes kernel panic.
2 SLES 11
GMC
OS sets default rports dev_loss_tmo value at 10 seconds
resulting in loss of the path during failover/failback.
3 RHEL 5.4 With FC switch, HBA driver (such as Emulex 4g, QLogic 8g)
sets rports dev_loss_tmo value too small, resulting in loss
of the path during failover/failback.
To fix this problem, increase the value to 60 seconds.
4 SLES 10
SP3
With FC switch, HBA driver (such as Emulex 4g, QLogic 8g)
sets rports dev_loss_tmo value too small, resulting in loss
of the path during failover/failback.
To fix this problem, increase the value to 60 seconds.
5 SLES 11
SP1
• With a FC HBA, set rports dev_loss_tmo as large as
possible, such as 0x7fffffff. Set fast_io_failure_tmo to
30 seconds. Without these settings, the system does
not recognize device or the systems hang during boot
and failover/failback.
• Download and update the latest SLES11 SP1 patches
from Novell. Without these patches, the system hangs
during failover/failback.