Rackable Systems OmniStor 4700S Series, User Manual

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Chapter 2 - Operating Mode and Topologies
Clustered Connection - Dual Hosts
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Clustered Connection - Dual Hosts
This topology supports standard current SCSI clustering infra-structure. Each host employs a
single ported SCSI HBA. Each SCSI bus is isolated and the LUNs are viewable on both SCSI
ports. In this configuration you will have two independent Ultra320 paths to the storage.
Expansion Connection
This topology supports standard single or dual ported direct attached access to the storage in
which additional enclosures are daisy-chained to to the primary enclosure. The host employs
a dual ported SCSI HBA or two single port SCSI HBAs. In this configuration you will have
two Ultra320 paths to the storage.
LUN Mapping
The SCSI-SATA RAID Controller has extensive support for LUN assignment and SAN
LUN Mapping. A logical drive can be mapped to a particular host HBA port. Up to 512
mappings or assignments can be created, with a 2 TB per logical drive limitation. Online
logical drive addition and deletion is supported, in any order.
SAN LUN Mapping allows multiple hosts and operating systems exclusive access to certain
areas of the storage without requiring host software for management. Additionally, an
internal logical drive can be presented to a host system as a different LUN number,
simplifying multiple systems setup.
Alternate Path Software
This is a software tool that manages multiple paths between the host operating system and
logical drives. The software manages the multiple paths by detecting duplicate disk objects
that represent a single logical drive. It then designates one disk object as the primary disk
object with a primary path, while the other is designated the secondary disk object with an
alternate path. If the primary path becomes inaccessible, the software redirects the data to
the secondary disk object through the alternate path, preserving the access to the logical
drive.