San Rules For Lun Masking; Using Device Mapper Multipath With Novell Cluster Services - Novell OPEN ENTERPRISE SERVER 2 SP 2 - CLUSTER SERVICES 1.8.7 FOR LINUX Manual

3.1.5 SAN Rules for LUN Masking

When you create a Novell Cluster Services system that uses shared storage space, it is important to
remember that all of the servers that you grant access to the shared device, whether in the cluster or
not, have access to all of the volumes on the shared storage space unless you specifically prevent
such access. Novell Cluster Services arbitrates access to shared volumes for all cluster nodes, but
cannot protect shared volumes from being corrupted by non-cluster servers.
LUN masking is the ability to exclusively assign each LUN to one or more host connections. With it
you can assign appropriately sized pieces of storage from a common storage pool to various servers.
See your storage system vendor documentation for more information on configuring LUN masking.
Software included with your storage system can be used to mask LUNs or to provide zoning
configuration of the SAN fabric to prevent shared volumes from being corrupted by non-cluster
servers.
IMPORTANT: We recommend that you implement LUN masking in your cluster for data
protection. LUN masking is provided by your storage system vendor.
3.1.6 Using Device Mapper Multipath with Novell Cluster
Services
When you use Device Mapper Multipath (DM-MP) with Novell Cluster Services, make sure to set
the path failover settings so that the paths fail when path I/O errors occur.
The default setting in DM-MP is to queue I/O if one or more HBA paths is lost. Novell Cluster
Services does not migrate resources from a node set to the Queue mode because of data corruption
issues that can be caused by double mounts if the HBA path is recovered before a reboot.
IMPORTANT: The HBAs must be set to Failed mode so that Novell Cluster Services can auto
failover storage resources if a disk paths go down.
Change the setting in the
Cluster Services works correctly with DM-MP. Also consider changes as needed for the retry
settings in the HBA BIOS.
"Settings for the modprobe.conf.local File" on page 38
"Settings for the multipath.conf File" on page 39
"Settings for a QLogic HBA BIOS" on page 39
Settings for the modprobe.conf.local File
Use the following setting in the
options qla2xxx qlport_down_retry=1
There was a change in the latest kernel and qla-driver that influences the time-out. Without the latest
patch, an extra five seconds is automatically added to the port_down_retry variable to determine the
time-out value for option 1 (dev_loss_tmo=port_down_retry_count+5), and option 1 is the best
choice. In the patch, the extra 5 seconds are no longer added to the port_down_retry variable to
determine the time-out value for option 1 (dev_loss_tmo=port_down_retry_count). If you have
installed the latest qla-driver, option 2 is the best choice.
38 OES 2 SP2: Novell Cluster Services 1.8.7 for Linux Administration Guide
modprobe.conf.local
/etc/modprobe.conf.local
and files so that Novell
multipath.conf
file: