Release Notes Device Mapper Multipath Enablement Kit for HP StorageWorks Disk Arrays v4.1.0 (AA-RWF9E-TE, November 2008)

NOTE:
Ensure you have a HBA driver installed in si ngle path mo de. For more information, see the installation
and reference guides for the respective HBA drivers.
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 command to check if the daemon is config ured to start at boot time:
# chkconfig --list multipathd
2. Run the following commands to start the Device Mapper Multipath daemon:
# chkconfig [--level levels] multipathd on
# chkconfig multipathd
For SLES 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]
Kno wn issues
Following are the known issues in the HPDM Multipath 4.1.0 release:
• Path failure messages are seen in the log file when encountered with a Unit Attention condition.
This behavior could be observed during online LUN addition, deletion, LUN transition across the
controller. These paths would be recovered after the polling interval set.
• multipath commands may take longer time to execute on heavily loaded servers or u nder
path failure conditions.
• User friendly multipath device names may change on reboot if /var is mounted on a separate
partition other than the root file system. It is recommended to have /(root) and /var on the
same partition.
• Blacklisting the multipath device in the file /etc/multipath.conf and restarting the multipath
service may not remove the device on RHEL 4 distributions. Execute the following command to
remove the blacklisted d evice:
# multipath -f <device>
• Using fdisk comm and to create par titions may fail to create Multipath d evice for the partition
device. It is recommended to use parted command to create pa rtitions for the device.
• multipathd daemon crashes on systems configured with device paths more than the system
open fi le 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 de vices 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.
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Device Mapper Multipath Enablement Kit for HP StorageWorks Disk Arrays