HP StorageWorks NAS 8000 - Version 1.6.X Release Note page 14

Exceeding the 128 logical path limit may cause unpredictable and undesired effects with your
storage. SAN managers should observe care in how LUNs are presented to the NAS 8000 by
using appropriate zoning techniques.
•
A logical path is a physical fibre-channel path from an HBA on the NAS 8000 through zero or
more switches to a port on a controller on a storage array that is presenting the LUN to the HBA.
There are typically 2 logical paths to each LUN on a dedicated attach system that does not use
switches, and 4 logical paths to each LUN on SAN attached systems or dedicated attach systems
using switches.
•
Use the following formula to calculate the total number of logical paths: For each LUN: Paths =
(Number of HBA's to which this LUN is presented) * (Number of ports on which this LUN is
presented).
•
You can reduce the number of paths by removing LUNs, zoning out ports, or removing cables to
unneeded ports.
•
The VA arrays always present LUN 0 for management purposes, even if this LUN has not been
created.
Losing All Paths to a LUN Causes File Volumes to Shutdown
•
If all paths to a LUN on a volume group fail, all file volumes on that volume group will shutdown.
Any access to the volumes will result in an I/O error until the volumes are repaired. To repair the
volumes, first restore the paths, then run the repairStorageVolumegroup command on the
affected volume groups. If you still get errors after running the command, reboot the node.
Data Path Manager Installation Process
•
There is a known issue that causes the Data Path Manager package to operate without its full
functionality after its initial installation. Specifically, automatic path failback will not be available
immediately after installing and enabling the Data Path Manager software package. This means
that paths that fail and are later restored will not automatically be re-used by the NAS 8000. The
solution to this problem is simply to reboot the NAS 8000 system after the Data Path Manager
package is installed and enabled. Data Path Manager will then operate with its full complement
of functionality, including automatic path failback.
HP StorageWorks NAS 8000
Version 1.6.3 Release Notes
Copyright Hewlett-Packard Co. 2003
This information is subject to change without notice and
is provided "as is" with no warranty.
Hewlett-Packard shall not be liable for any direct,
indirect, special, incidental or consequential damages
in connection with the use of this material
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