Справочник Пользователя для IBM Flex System V7000 Expansion Enclosure 4939H29

Draft Document for Review January 29, 2013 12:52 pm

IBM Flex System V7000 Storage Node Introduction and Implementation Guide

Some virtualization functions are not available for image mode volumes, so it is often useful to 
migrate the volume into a new storage pool. After it is migrated, the MDisk becomes a 
managed MDisk.

If you add an MDisk containing data to a storage pool, any data on the MDisk is lost. Ensure 
that you create image mode volumes from MDisks that contain data before adding MDisks to 
the storage pools.

Volumes can be configured to either be 

 or 

. A thin-provisioned 

volume behaves with respect to application reads and writes as though they were fully 
allocated. When a volume is created, the user specifies two capacities: the real capacity of 
the volume and its virtual capacity.

The real capacity determines the quantity of MDisk extents that are allocated for the volume. 
The virtual capacity is the capacity of the volume reported to IBM Flex System V7000 Storage 
Node and to the host servers.

The real capacity is used to store both the user data and the metadata for the thin-provisioned 
volume. The real capacity can be specified as an absolute value or a percentage of the virtual 
capacity.

The thin provisioning feature can be used on its own to create overallocated volumes, or it can 
be used with FlashCopy. Thin-provisioned volumes can be used with the mirrored volume 
feature as well. 

A thin-provisioned volume can be configured to 

, which causes IBM Flex System 

V7000 Storage Node to automatically expand the real capacity of a thin-provisioned volume 
as its real capacity is used. Autoexpand attempts to maintain a fixed amount of unused real 
capacity on the volume. This amount is known as the 

.