Storage Capacity Virtualization
Thin Provisioning improves the usability of the drives by managing the physical drives in a pool, and sharing the
unused capacity among the virtual volumes in the pool. The volume capacity that is seen from the server is
virtualized to allow the server to recognize a larger capacity than the physical volume capacity. Because a large
capacity virtual volume can be defined, the drives can be used in a more efficient and flexible manner.
Initial cost can be reduced because less drive capacity is required even if the capacity requirements cannot be
estimated. The power consumption requirements can also be reduced because a fewer number of drives are
installed.
Figure 20
Storage Capacity Virtualization
Virtual volume
Data that is
actually used
Mapping
Write
Allocated as required
Allocated
Physical drives
RAID group
Management server
In the Thin Provisioning function, the RAID group, which is configured with multiple drives, is managed as a Thin
Provisioning Pool (TPP). When a write request is issued from the host, a physical area is allocated to the virtual
volume. The free space in the TPP is shared among the virtual volumes which belong to the TPP, and a virtual
volume, which is larger than the drive capacity in the ETERNUS AF, can be created. A virtual volume to be
created in a TPP is referred to as a Thin Provisioning Volume (TPV).
•
Thin Provisioning Pool (TPP)
A TPP is a physical drive pool which is configured with one or more RAID groups. TPP capacity can be expanded
in the units of RAID groups. Add RAID groups with the same specifications (RAID level, drive type, and number
of member drives) as those of the existing RAID groups.
The following table shows the maximum number and the maximum capacity of TPPs that can be registered in
the ETERNUS AF.
Table 20
TPP Maximum Number and Capacity
Item
ETERNUS AF150 S3
ETERNUS AF250 S3
ETERNUS AF650 S3
Maximum number of pools (*1) 12
132
256
Maximum pool capacity (*2)
4,096TB
6,144TB
24,576TB
*1:
The maximum total number of Thin Provisioning Pools and FTSPs.
*2:
The maximum pool capacity is the capacity that combines the FTSP capacity and the Thin Provisioning Pool capacity in the ETERNUS
AF.
2. Basic Functions
Operations Optimization (Deduplication/Compression and Storage Virtualization)
50
Design Guide
Summary of Contents for ETERNUS AF S3 Series
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