Assign Dedicated Hot Spare - Fujitsu ETERNUS DX60 S3 User Manual

Chapter 2 Component Management

2.3 Assign Dedicated Hot Spare

2.3 Assign Dedicated Hot Spare
This function registers a drive as a Dedicated Hot Spare for a RAID group.
A Dedicated Hot Spare is a spare drive (hot spare) that is registered in the RAID group instead of the failed
drive when a drive failure occurs. A Dedicated Hot Spare, unlike a Global Hot Spare, is used only for the specific
RAID group.
If a drive fails, data copy (rebuild) to a Dedicated Hot Spare starts automatically.
If the Copybackless function is disabled and the failed drive is replaced with a normal drive, the data is copied
back to the replacement drive. The Dedicated Hot Spare that is used instead of the failed drive then returns as
a spare drive.
If the Copybackless function (*1) is enabled, the Hot Spare is registered in the RAID group after rebuilding and
is used as a data drive. The failed drive in the RAID group is changed to a Dedicated Hot Spare after the
rebuilding is complete. If the failed drive is replaced with a normal drive, the replacement drive can be used
as a Dedicated Hot Spare.
*1: "Copybackless" is a function that mounts a hot spare in the RAID group instead of the failed drive. The replaced drive
is then used as a hot spare. This function makes Copyback unnecessary.
• Drives that are currently used cannot be registered as Dedicated Hot Spares.
• Make sure to register a Dedicated Hot Spare with the same or a larger capacity than the data drives. If the
Dedicated Hot Spare capacity is smaller than the data drive, the drive does not work as the hot spare.
• When a mix of Online disks, Nearline disks, SSDs, Online SEDs, Nearline SEDs, and SSD SEDs is installed
together in the ETERNUS DX, Dedicated Hot Spare of each type is required. Register the Dedicated Hot
Spare with the same capacity as the maximum capacity drive for each type.
• When multiple types of SSDs (SSD-M/SSD/SSD-M SED) are installed together in the ETERNUS DX, a Dedi-
cated Hot Spare for each type is required. Register the Dedicated Hot Spare with the same capacity as the
maximum capacity SSD for each type.
• Only one RAID group can be registered for each Dedicated Hot Spare. A Dedicated Hot Spare cannot be
registered to multiple RAID groups.
• The Dedicated Hot Spares cannot be registered in the following RAID groups.
- RAID groups that belong to TPPs
- RAID groups that belong to FTSPs
- RAID groups that are registered as REC Disk Buffers
- RAID groups that are registered as EXCPs
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