Fujitsu ETERNUS DX S5 Series - Flexible Tier; Table 32 Chunk Size and Data Transfer Unit

Flexible Tier
Flexible Tier provides the following functions:
• Automated Storage Tiering
This function automatically reallocates data according to the data access frequency and optimizes
performance and cost.
• FTRP Balancing
I/O access to a virtual volume can be distributed among the RAID groups in a pool by relocating and balancing
the physical areas allocated to the virtual volume.
• TPV/FTV Capacity Optimization
Data in physically allocated areas are checked in blocks and unnecessary areas (areas where 0 is allocated to
all of the data in each block) are released to unallocated areas.
For details on these functions, refer to "TPV/FTV Capacity Optimization" (page
64).
• Automated QoS
The QoS for each volume can be controlled by using the ETERNUS SF Storage Cruiser's QoS management
option.
For details on Automated QoS, refer to the ETERNUS SF Storage Cruiser manual.
Automated Storage Tiering
The ETERNUS DX uses the Automated Storage Tiering function of ETERNUS SF Storage Cruiser to automatically
change data allocation during operations according to any change in status that occurs. ETERNUS SF Storage
Cruiser monitors data and determines the redistribution of data. The
ETERNUS DX uses the Flexible Tier function
to move data in the ETERNUS DX according to requests from ETERNUS SF Storage Cruiser.
The Flexible Tier function automatically redistributes data in the ETERNUS DX according to access frequency in
order to optimize performance and reduce operation cost. Storage tiering (SSDs, SAS disks, Nearline SAS disks) is
performed by moving frequently accessed data to high speed drives such as SSDs and less frequently accessed
data to cost effective disks with large capacities. Data can be moved in blocks (252MB) that are smaller than the
volume capacity.
The data transfer unit differs depending on the chunk size. The following table shows the relationship between
the data transfer unit and the chunk size.
Table 32 Chunk Size and Data Transfer Unit
Chunk size Transfer unit
21MB 252MB
42MB 504MB
84MB 1,008MB
168MB 2,016MB
336MB 4,032MB
With the Automated Storage Tiering function, Nearline SAS disks can be used to reduce installation costs and
retain performance.
Furthermore, because data is reallocated automatically, it can reduce the workload on the administrator for
designing storage performance.
2. Basic Functions
Operations Optimization (Virtualization/Automated Storage Tiering)
65 Design Guide