Device Mapper Multipath Enablement Kit for HP StorageWorks Disk Arrays v4.3.1 release notes (AA-RWF9J-TE, November 2009)

c. Edit the value for default parameter in /boot/grub/menu.lst file to boot with the new
initrd image.
SAN configuration supported by DM Multipath
Table 2 lists the maximum SAN configuration supported by DM Multipath.
Table 2 Maximum SAN configuration supported by DM Multipath
512Maximum number of LUNs supported
32Maximum number of paths per LUN
8Maximum number of HBAs
2048Total number of SAN devices
NOTE:
If the total number of LUNs is 512, each LUN can have 4 paths which leads to 2048 (512*4) devices.
Maximum SAN configuration supported by DM Multipath is only on SLES 11 operating systems.
Known issues
Following are the known issues in the HPDM Multipath 4.3.1 release:
• multipath commands may take longer time to execute on heavily loaded servers or under path
failure conditions.
• Blacklisting the multipath device in the /etc/multipath.conf file and restarting the multipath
service may not remove the device on RHEL 4 distributions. Execute the following command to
remove the blacklisted device:
# multipath -f <device>
• 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.
• Multipath -l command may not reflect the correct path status for Logical Units presented from
MSA2xxxsa array when paths fail or are restored under heavy load conditions. To refresh the
path status, execute the # multipath -v0 command.
• 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 the /etc/multipath.conf file or
by using the ulimit -n command and restart the multipathd demon.
• 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.
• If an existing LUN is deleted or unpresented from RHEL host, a DM multipath device with the invalid
WWN may be created which cannot be used and will be removed after the system reboots.
• For LUNs greater than 2TB in RHEL 4 operating systems, DM multipath devices may not be created
with appropriate size.
• On RHEL 4 operating systems with large number of iSCSI devices, not all multipath devices may
get created after a reboot. It is recommended to increase the ESTABLISHTIMEOUT value in the
Device Mapper Multipath Enablement Kit for HP StorageWorks Disk Arrays v4.3.1 release notes 13