Specifications

C-4

Cisco UCS C220 Server Installation and Service Guide

OL-25760-01

Appendix C RAID Controller Considerations

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 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.

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 Ye s

SAS SSD + SATA SSD Yes

HDD + SSD No