Flexible Tier; Table 19 Chunk Size And Data Transfer Unit - Fujitsu ETERNUS AF250 Design Manual

1. Function
Operations Optimization (Deduplication/Compression and Storage Virtualization)

Flexible Tier

The Flexible Tier function has the following functions:
Automated Storage Tiering
•
This function automatically reallocates data according to the data access frequency and optimizes perform-
ance 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 allocation status of the 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
QoS automation function
•
The QoS for each volume can be controlled by using the ETERNUS SF Storage Cruiser's QoS management op-
tion.
For details on the QoS automation function, refer to the ETERNUS SF Storage Cruiser manual.
Automated Storage Tiering
The ETERNUS AF 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 AF uses the Flexible Tier function
to move data in the storage system according to requests from ETERNUS SF Storage Cruiser.
The Flexible Tier function automatically redistributes data in the ETERNUS AF in the hierarchical storage accord-
ing to the access frequency by setting the access priority of each RAID level and SSD type (MLC SSD and Value
SSD). 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 19 Chunk Size and Data Transfer Unit

Chunk size
21MB
42MB
84MB
168MB
The Automated Storage Tiering function allows proper use of high write endurance MLC SSDs and large capacity
Value SSDs, and allows the optimization of the RAID levels according to the performance and the storage effi-
ciency.
Furthermore, because data is reallocated automatically, it can reduce the workload on the administrator for de-
signing storage performance.
The Flexible Tier uses pools configured by multiple RAID groups (Flexible Tier Sub Pools: FTSP) and larger pools
comprised by layers of Flexible Tier Sub Pools (Flexible Tier Pools: FTRP). A volume which is used by the Flexible
Tier is referred to as the Flexible Tier Volume (FTV).
"TPV/FTV Capacity Optimization" (page
FUJITSU Storage ETERNUS AF250 S2, ETERNUS AF250 All-Flash Arrays Design Guide (Basic)
Copyright 2019 FUJITSU LIMITED
Transfer unit
252MB
504MB
1,008MB
2,016MB
52
51).
P3AG-1822-09ENZ0