System information

Most controllers use vendor-specific tools to query and manipulate target drives. For example, the
LSI Megaraid SAS controller uses a battery-backed write cache; this type of controller requires the
Meg aC l i 6 4 tool to manage target drives. To show the state of all back-end drives for LSI Megaraid
SAS, use:
# MegaCli64 -LDGetProp -DskCache -LAll -aALL
To disable the write cache of all back-end drives for LSI Megaraid SAS, use:
# MegaCli64 -LDSetProp -DisDskCache -Lall -aALL
Note
Hardware RAID cards recharge their batteries while the system is operational. If a system is
powered off for an extended period of time, the batteries will lose their charge, leaving stored
data vulnerable during a power failure.
High-End Arrays
High-end arrays have various ways of protecting data in the event of a power failure. As such, there
is no need to verify the state of the internal drives in external RAID storage.
NFS
NFS clients do not need to enable write barriers, since data integrity is handled by the NFS server
side. As such, NFS servers should be configured to ensure data persistence throughout a power loss
(whether through write barriers or other means).
High- End Arrays
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