Device Mapper Multipath Enablement Kit for HP StorageWorks Disk Arrays v4.2.1 release notes (AA-RWF9H-TE, March 2009)

Setting up Device Mapper Multipath daemon

You must set the Device Mapper Multipath daemon to start at boot time.

For RHEL hosts, complete the following steps to start the multipathd daemon at boot time:

1. Run the following commands to check if the daemon is configured to start at boot time:

# chkconfig --list boot.device-mapper

# chkconfig --list boot.multipath

# chkconfig --list multipathd

2. Run the following commands to start the Device Mapper Multipath daemons:

# chkconfig boot.device-mapper [levels]

# chkconfig boot.multipath [levels]

Known issues

Following are the known issues in the HPDM Multipath 4.2.1 release:

• Path failure messages are seen in the log file when encountered with a Unit Attention condition.

This behavior can be observed during online LUN addition, deletion, LUN transition across the

controller. These paths can be recovered after the polling interval set.

• multipath commands may take longer time to execute on heavily loaded servers or under path

failure conditions.

• User friendly multipath device names may change on reboot if /var is mounted on a partition

other than the root file system. It is recommended to have /(root) and /var on the same partition

or change the multipath bindings file location using the 'bindings_file' parameter in the

/etc/multipath.conf file.

• Using fdisk command to create partitions may fail to create Multipath device for the partition

device. It is recommended to use parted command to create partitions for the device.

• multipathd daemon crashes on systems configured with device paths more than the system

open file limits (default system open file limit=1024). It is recommended to change the system open

file limits by using either the 'max_fds' parameter in /etc/multipath.conf file or by using

the ulimit -n command and restart the multipathd demon.

• Multipath -l command may not reflect the correct path status for Logical Units presented from

MSA2012sa array when paths fail or are restored under heavy load conditions. To refresh the

path status, execute the # multipath -v0 command.

• Multipath devices may not be created for Logical Units when the system disks or internal controllers

are cciss devices. It is recommended to blacklist these devices in the /etc/multipath.conf

file and restart the multipathd daemon.

Support

Telephone numbers for worldwide technical support are listed on the HP support website:

http://www.hp.com/support/

Collect the following information before calling the worldwide technical support:

• Technical support registration number (if applicable)

• Product serial numbers