Figure 24 Flexible Tier; Table 17 Chunk Size And Data Transfer Unit - Fujitsu ETERNUS DX100 S4 Design Manual

2. Basic Functions
Operations Optimization (Virtualization/Automated Storage Tiering)
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 oc-
curs. 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 storage system according to re-
quests 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 relation-
ship between the data transfer unit and the chunk size.

Table 17 Chunk Size and Data Transfer Unit

Chunk size
21MB
42MB
84MB
168MB
By using the Automated Storage Tiering function, installation costs can be reduced because Near-
line SAS disk, which maintain performance, can be used.
Furthermore, because data is reallocated automatically, it can reduce the workload on the adminis-
trator for designing storage performance.

Figure 24 Flexible Tier

Management server
ETERNUS SF
Storage Cruiser
Fujitsu Storage ETERNUS DX100 S4/DX200 S4, ETERNUS DX100 S3/DX200 S3 Hybrid Storage Systems Design Guide (Basic)
Monitors the data access frequency
and optimizes performance
Access frequency
High
Low
Work volume
Copyright 2023 Fujitsu Limited
Transfer unit
252MB
504MB
1,008MB
2,016MB
High speed SAS disk
49
ETERNUS DX
High speed SSD
Large capacity
and cheap
Nearline SAS
disk
P3AM-7642-32ENZ0