After server reboot multipath shows no paths.

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Environment

SUSE Linux Enterprise Server 11 Service Pack 3 (SLES 11 SP3)
SUSE Linux Enterprise Server 11 Service Pack 4 (SLES 11 SP4)
Fiber Channel over Ethernet (FCoE)
Network Bonding

Situation

When using Fiber Channel over Ethernet (FCoE) along with NetWork bonding, after every reboot multipath shows no paths, executing "multipath -ll" returns nothing. The following is an example of messages that will be logged for every path in "/var/log/messages":

Jan 1 13:00:00 myserver_name multipathd: my_path: path state = blocked

Manually restarting multipath using "rcmultipathd restart" or forcing a devmap reload using "multipath -r" once the server is up and running after a reboot may resolve the issue until the next reboot.

Resolution

Verify that the bonding network device is not configured to use "Dynamic Link Aggregation" (802.3ad), replace this with for example "balance-tlb" instead. This can be done by editing "/etc/sysconfig/network/ifcfg-bond0" and adjusting the "BONDING_MODULE_OPTS" line to read as follows:

BONDING_MODULE_OPTS='mode=balance-tlb miimon=100'

It likely will also be required to make changes to the network switch configurations, for example disabling switch assisted load balancing.

Cause

Using Fiber Channel over Ethernet (FCoE) along with Link Aggregation can cause the Host Bus Adapter (HBA) to not detect and setup the storage devices properly resulting in multipath failing.

Additional Information

For more details on the different available bonding modes see the following file on a server that has the kernel-source package installed: /usr/src/linux/Documentation/networking/bonding.txt

Disclaimer

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