Specifications

28 en | RAID Planning SCSI to SATA RAID Subsystem | Administrator’s Manual
F.01U.027.802 | V1 | 2006.11 Bosch Security Systems
2.3.3 Making Arrays Available to Hosts
Fig. 2.7 Mapping Partitions to Host ID/LUNs
Host ID mapping is a process that associates a logical configuration of drives with a host chan-
nel ID/LUN. To avail logical partitions on host channel(s), map each partition to a host ID or
one of the LUNs under host IDs. Each ID or LUN will appear to the host adapter as one virtual
hard drive.
There are alternatives in mapping for different purposes:
1. Mapping a logical configuration to IDs/LUNs on different host channels allows two host
computers to access the same array. This method is applicable when the array is shared
in a clustering configuration. Multi-path management software is required on the host
side to avoid access contention.
2. Mapping partitions of an array to IDs/LUNs across separate host channels can distribute
workload over multiple data paths.
3. Mapping across separate host channels also helps to make use of all bandwidth in a
multi-path configuration. Firmware automatically manages the process when one data
path fails and the workload on the failed data path has to be shifted to the existing data
paths.
Fig. 2.8 Mapping in a Multi-path Environment