C-4
Cisco UCS C220 Server Installation and Service Guide
OL-25760-01
Appendix C RAID Controller Considerations
Mixing Drive Types in RAID Groups
Mixing Drive Types in RAID Groups
Table C-3 lists the technical capabilities for mixing hard disk drive (HDD) and solid state drive (SSD)
types in a RAID group. However, see the best pract
ices 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.
RAID Backup Units
This server supports installation of one SuperCap Power Module (SCPM). The unit mounts to a holder
on the left-side air baffle (see Figure 3-24).
Note The iBBU09 battery backup unit (BBU) has been phased out by Cisco and replaced with the SuperCap
power module (SCPM). If you are replacing a BBU, order the SCPM for the replacement
(UCS-RAID-CV-SC=). Cards that used the BBU are compatible with the SCPM.
• The optional SCPM provides approximately 3 years of backup for the disk write-back cache DRAM
in the case of sudden power loss by offloading the cache to the NAND flash.
Ta b l e C-3 Drive Type Mixing in RAID Groups
Mix of Drive Types
in RAID Group Allowed?
SAS HDD + SATA HDD Yes
SAS SSD + SATA SSD Ye s
HDD + SSD No