IBM SAN Volume Controller

Terminology

Node - a single 1U machine.

SVC node models
Type-model	Cache	FC speed	iSCSI Speed	Based upon	Announced
2145-4F2	4	2	n/a	x335	2 June 2003
2145-8F2	8	2	1	x336	25 October 2005
2145-8F4	8	4	1	x336	23 May 2006
2145-8G4	8	4	1	x3550	22 May 2007
2145-8A4	8	4	1	x3250	28 October 2008
2145-CF8	24	8	1	x3550M2	20 October 2009
2145-CG8	24	8	1 (10 Gbit/s optional)	x3550M3	5 May 2011

I/O group - a pair of nodes that duplicate each other's write commands
Cluster - a group of 1 to 4 I/O groups managed as a single entity.
- Stretched cluster - a site protection configuration with 1 to 4 I/O groups, each stretched across two sites, plus a witness site
- Cluster IP address - a single IP address of a cluster that provides administrative interfaces via (SSH and HTTPS)
- Service IP address - an IP address used to service an individual node. Each node can have a service IP configured.
- Configuration node - a single node that holds the cluster's configuration and has the assigned cluster IP address.
Master Console (or SSPC) - a management GUI for SVC until rel 5.1, based on WebSphere Application Server; not installed on any SVC node, but on a separate machine
- As of SVC rel 6.1, a Master Console (SSPC) is no longer used. Web based administration is done directly on the configuration node, using a HTML5 GUI.
Virtual Disk (VDisk) - a unit of storage presented to the host. The release 6 GUI refers to a VDisk as a Volume.
Managed Disk (MDisk) - a unit of storage (a LUN) from a real, external disk array, virtualized by the SVC. An MDisk is the base to create an image mode VDisk.
Managed Disk Group - (MDisk Group) a group of one or more Mdisks. The extents of the MDisks in an MDisk Group are the base to create a striped or sequential mode VDisk. The release 6 GUI refers to a Managed Disk Group as a Pool.
Extent - a discrete unit of storage; an MDisk is divided into extents; a VDisk is formed from set of extents.