IBM Storwize V5010 Manual page 848

Hop
One segment of a transmission path between adjacent nodes in a routed network.
Host bus adapter
A host bus adapter (HBA) is an interface card that connects a server to the SAN environment
through its internal bus system, for example, PCI Express. Typically it is referred to the Fibre
Channel adapters.
Host ID
A host ID is a numeric identifier that is assigned to a group of host FC ports or Internet Small
Computer System Interface (iSCSI) host names for LUN mapping. For each host ID, SCSI IDs
are mapped to volumes separately. The intent is to have a one-to-one relationship between
hosts and host IDs, although this relationship cannot be policed.
Host mapping
Host mapping refers to the process of controlling which hosts have access to specific
volumes within a cluster (host mapping is equivalent to LUN masking).
Hot extent
A hot extent is a frequently accessed volume extent that gets a performance benefit if it is
moved from an HDD onto a Flash Disk.
Hot Spare node (SVC only)
Hot Spare Node is an online SVC node defined in a cluster but not in any IO group. In case of
a failure of any of online nodes in any IO group of cluster, it will be automatically swapped by
this Spare node. Once the recovery of an original node has finished, the Spare node gets
back to the standby spare status. This feature is not available for IBM Storwize V5000.
HyperSwap
Pertaining to a function that provides continuous, transparent availability against storage
errors and site failures, and is based on synchronous replication.
Image mode
Image mode is an access mode that establishes a one-to-one mapping of extents in the
storage pool (existing LUN or (image mode) MDisk) with the extents in the volume.
Image volume
An image volume is a volume in which a direct block-for-block translation exists from the
managed disk (MDisk) to the volume.
I/O Group
Each pair of IBM Storwize V5000 canisters is known as an input/output (I/O) Group. An I/O
Group has a set of volumes that are associated with it that are presented to host systems.
Each Storwize V5000 canister is associated with exactly one I/O Group. The canister in an
I/O Group provide a failover and failback function for each other. An IBM Storwize V5000
cluster consist of two I/O groups.
Internal storage
Internal storage refers to an array of managed disks (MDisks) and drives that are held in IBM
Storwize V5000 enclosures.
826
Implementing the IBM Storwize V5000 Gen2 with IBM Spectrum Virtualize V8.1