## Striped 

Pertaining to a volume that is created from multiple MDisks that are in the storage pool. Extents are allocated on the MDisks in the order specified. 

## Support Assistance 

A function that is used to provide support personnel remote access to the system to perform troubleshooting and maintenance tasks. 

## Symmetric virtualization 

Symmetric virtualization is a virtualization technique in which the physical storage, in the form of a RAID, is split into smaller chunks of storage known as extents. These extents are then concatenated, by using various policies, to make volumes. See also “Asymmetric virtualization” on page 796. 

## Synchronous replication 

Synchronous replication is a type of replication in which the application write operation is made to both the source volume and target volume before control is given back to the application. See also “Asynchronous replication” on page 796. 

## Tie-break 

In a case of a cluster split in 2 groups of nodes, tie-break is a role of a quorum device used to decide which group continues to operate as the system, handling all I/O requests. 

## Thin-provisioned volume 

A thin-provisioned volume is a volume that allocates storage when data is written to it. 

## Thin provisioning 

Thin provisioning refers to the ability to define storage, usually a storage pool or volume, with a “logical” capacity size that is larger than the actual physical capacity that is assigned to that pool or volume. Therefore, a thin-provisioned volume is a volume with a virtual capacity that differs from its real capacity. Before SVC V6.1, this thin-provisioned volume was known as space efficient . 

## Thin provisioning savings 

See “Capacity” on page 797. 

## Throttles 

Throttling is a mechanism to control the amount of resources that are used when the system is processing I/Os on supported objects. The system supports throttles on hosts, host clusters, volumes, copy offload operations, and storage pools. If a throttle limit is defined, the system either processes the I/O for that object, or delays the processing of the I/O to free resources for more critical I/O operations. 

## Transparent Cloud Tiering 

Transparent Cloud Tiering is a separately installable feature of IBM Spectrum Scale™ that provides a native cloud storage tier. 

## Total capacity savings 

See “Capacity” on page 797. 

