Fujitsu ETERNUS DX500 S4/DX600 S4 Design Manual page 183

5. Hardware Configurations
Optional Product Installation Conditions
Nearline SAS disks are used to store data that does not need the access performance of SAS disks. They are
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far more cost effective than SAS disks. It is recommended that SAS disks be used for data that is constantly
accessed or when high performance/reliability is required.
If the ambient temperature exceeds the operating environment conditions, Nearline SAS disk performance
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may be reduced.
Nearline SAS disks can be used as Advanced Copy destinations and for the storage of archived data.
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• When Nearline SAS disks are used as an Advanced Copy destination, delayed access responses and slower
copy speeds may be noticed, depending on the amount of I/O and the number of copy sessions.
• The following disks are Advanced Format (512e) disks.
2.5" Nearline SAS disks (2TB)
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3.5" Nearline SAS disks (6TB)
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3.5" Nearline SAS disks (8TB)
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3.5" Nearline SAS disks (10TB)
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- 3.5" Nearline SAS disks (12TB)
3.5" Nearline SAS disks (14TB)
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3.5" Nearline SAS self encrypting disks (8TB)
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3.5" Nearline SAS self encrypting disks (12TB)
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When using Advanced Format (512e) disks, make sure that Advanced Format (512e) is supported by the
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server OS and the applications. If the server OS and applications do not support Advanced Format (512e),
random write performance may be reduced.
For details on the RAID levels that can be configured with Nearline SAS disks that have 6TB or more, refer to
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"Supported RAID" (page
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SSDs
SSDs are reliable drives with high performance. SSDs are used to store high performance databases and other
frequently accessed data.
Flash memory as a storage media provides better random access performance than disks such as SAS disks and
Nearline SAS disks. Containing no motors or other moving parts, they are highly resistant to impact.
The ETERNUS DX supports SSDs that have a high level wear leveling function and sufficient reserved space. Note
that if the expected total write capacity is exceeded, the frequency of errors gradually increases, which may lead
to a reduction in the write performance. The ETERNUS DX has a function that shows the remaining capacity as a
percentage (health) in proportion to the expected total write capacity.
The number of rewrites may exceed the limit within the product warranty period if SSDs are used in a RAID1
configuration that has a high I/O access load. Using a RAID1+0, RAID5, RAID5+0, or RAID6 configuration is rec-
ommended.
The following types of SSDs are supported in the ETERNUS DX.
MLC SSDs (with a 12Gbit/s or a 6Gbit/s interface speed) that are compatible with Extreme Cache Pools
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Value SSDs (with a 12Gbit/s interface speed) that are incompatible with Extreme Cache Pools
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Value SSDs are available at a lower cost per capacity than conventional SSDs by optimizing the guaranteed write
endurance and the reserved space.
When random access (especially with write access) continues for several hours, the performance of Value SSDs
may be reduced compared with MLC SSDs that support Extreme Cache Pool.
Note that the product's actual capacity of a Value SSD differs from the capacity that is displayed in ETERNUS Web
GUI and ETERNUS CLI. For example, 2.00TB is displayed for a 1.92TB Value SSD.
FUJITSU Storage ETERNUS DX500 S4/DX600 S4, ETERNUS DX500 S3/DX600 S3 Hybrid Storage Systems Design Guide (Basic)
16).
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