•
If the free capacity in the FTSP becomes insufficient while FTRP balancing is being performed, an error oc-
curs and the balancing session ends abnormally. Note that insufficient physical capacity cannot be replaced
by other FTSPs.
•
When FTRP balancing is performed, an area for the work volume (the destination FTV which has the same
capacity as the source FTV) is secured in the FTRP to which the FTV belongs. As a result, the status of the
FTRP may temporarily become alarm status (the FTRP usage exceeds the "Caution" or "Warning" threshold).
This alarm state is removed once balancing completes successfully.
•
If the capacity of the FTRP is expanded during an FTRP balancing process, the balancing level might be less
than before.
•
FTRP balancing may not be performed regardless of what FTRP balancing level is used. FTRP balancing
availability depends on the physical allocation status of FTVs.
Extreme Cache
The Extreme Cache function uses PCIe Flash Modules (PFM) that are installed in the controller (CM) as the sec-
ondary cache to improve the read access performance from the server.
Frequently accessed areas are written to the PFM asynchronously with I/O. When a read request is issued from
the server, data is read from the PFM to speed up the response.
Either the Extreme Cache function or the Extreme Cache Pool function can be used. Using the faster Extreme
Cache function is recommended.
Figure 28 Extreme Cache
ETERNUS DX
PFM
Cache memory
Disks
Controller
Read request
When there is a read
request, the response
for the request will be
faster by reading data
from the PFM instead
of reading data from
the disks.
Frequently accessed
areas are written to
the PFM
The Extreme Cache function can be enabled or disabled for each volume. Note that the Extreme Cache function
cannot be enabled for Deduplication/Compression Volumes, or volumes that are configured with SSDs.
The Extreme Cache function may improve random I/O.
2. Basic Functions
Operations Optimization (Virtualization/Automated Storage Tiering)
55
FUJITSU Storage ETERNUS DX500 S4/DX600 S4, ETERNUS DX500 S3/DX600 S3 Hybrid Storage Systems Design Guide (Basic)
Copyright 2019 FUJITSU LIMITED
P3AM-7722-25ENZ0
Summary of Contents for ETERNUS DX500 S3/DX600 S3
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