Cisco UCS C240 M5 Service Manual

Write-Cache Policy for Cisco 12G SAS Modular RAID Controllers
For this server and other Cisco Generation M5 servers, the default write-cache policy for the Cisco Modular
RAID controllers is Write Through (irrespective of the presence of a charged supercap or “good BBU”). This
utilizes the optimal performance characteristics of the controller.
The write policy can be set to Write Back, if preferred. You can set the write policy using the following
methods:
•
For standalone servers, use the Cisco IMC interface to set Virtual Drive Properties > Write Policy. See
the “Managing Storage Adapters” section in your Cisco IMC Configuration Guide.
Cisco IMC GUI and CLI Configuration Guides
•
For Cisco UCS-integrated servers, use the Cisco UCS Manager interface to set the write-cache policy
as part of virtual drive configuration in your storage profile.
Cisco UCS Manager Configuration Guides
•
Use the LSI Option ROM Configuration Utility.
Mixing Drive Types in RAID Groups
The following table lists the technical capabilities for mixing hard disk drive (HDD) and solid state drive
(SSD) types in a RAID group. However, see the recommendations that follow for the best performance.
Table 17: Mixing Drive Types
Allowed?Mix of Drive Types in RAID Group
YesSAS HDD + SATA HDD
YesSAS SSD + SATA SSD
NoHDD + SSD
Drive Type Mixing Best Practices
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.
Cisco UCS C240 M5 Server Installation and Service Guide
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Storage Controller Considerations
Write-Cache Policy for Cisco 12G SAS Modular RAID Controllers

Cisco UCS C240 M5 Specifications

General

Form Factor	2U Rack
Storage Controllers	Cisco 12G SAS Modular RAID Controller
Management	Cisco Integrated Management Controller (CIMC)
Processor	Intel Xeon Scalable Processors
Memory	Up to 3TB DDR4
Drive Bays	Up to 12 x 3.5-inch drives