
C-2
Cisco UCS C460 Server Installation and Service Guide
OL-22326-01
Appendix C RAID Controller Considerations
Mixing Drive Types in RAID Groups
Mixing Drive Types in RAID Groups
Table C-2
lists the technical capabilities for mixing hard disk drive (HDD) and solid state drive (SSD)
types in a RAID group. However, see the best practices recommendations that follow for the best
performance.
Best Practices For Mixing Drive Types in RAID Groups
For the best performance, follow these guidelines:
•
Use either all SAS or all SATA drives in a RAID group.
•
Use the same capacity for each drive in the RAID group.
•
Never mix HDDs and SSDs in the same RAID group.
Battery Backup Unit
T
his server
supports installation of one LSI RAID battery backup unit (BBU). The unit mounts to the
chassis wall (see
Replacing the SAS Riser Battery Backup Unit, page 3-18
).
The optional LSI BBU is available only when using an LSI MegaRAID 9260-8i controller card. This
BBU provides approximately 72 hours of battery backup for the disk write-back cache DRAM in the
case of sudden power loss.
RAID Controller Cabling
This section includes the following topics:
•
Cable Routing, page C-2
•
Cisco UCS C460 Server Cabling, page C-4
Cable Routing
The red line in
Figure C-1
shows the recommended cable routing path from the backplane to the SAS
riser connectors.
Table C-2
Drive Type Mixing in RAID Groups
Mix of Drive Types
in RAID Group
Allowed?
SAS HDD + SATA HDD
Yes
SAS SSD + SATA SSD
Yes
HDD + SSD
No