System Password Reset; Cache Functions And Features; Cache Mirroring; Write-Back Cache - Dell PowerVault MD3800f Owner's Manual

Temperature threshold values determine the temperature at which shutdown occurs. These thresholds
cannot be changed.
Table 6. Shutdown Threshold Type
Threshold Temperature Exceeding
Nominal failure threshold
Maximum failure threshold
Shutdown threshold

System Password Reset

The storage array password can be reset if it is forgotten. To reset the password, push and hold down the
password reset switch for at least 5 seconds. The password is deleted.
The RAID controller module allows you to change the password.
NOTE: The reset switch can be accessed by using a small object such as the tip of a pen.
NOTE: The password reset switch is not available if your system was shipped after September, 2015.
The password reset switch functionality was disabled starting from controller firmware 08.20.09.60
and later versions.

Cache Functions and Features

Cache Mirroring

Cache mirroring function copies accepted host-write data from the primary controller to the partner
controller. This action ensures that host-write data is safely mirrored to the partner controller before
successful completion status is returned to the host. If a controller fails, the surviving controller safely
retains all mirrored data. Cache mirroring is enabled by default.

Write-Back Cache

In write-back cache, write operations result in a completion signal being sent to the host operating
system as soon as the cache receives the data to be written. The target physical disk receives the data at a
more appropriate time to increase controller performance. In dual-active controller configurations with
write-back caching enabled, the write data is always mirrored to the cache of the second controller
before completion status is issued to the host initiator. Write-back cache is enabled by default unless
cache mirroring is disabled.

Write-Through Cache

In write-through cache, data is written to the physical disk before completion status is returned to the
host operating system. Write-through cache is considered more robust than write-back cache, since a
Event Description
A critical event is set.
Shutdown of the system power supplies
occurs within 3 minutes.
Shutdown of the system power supplies
occurs within 5 seconds.
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