Supermicro AOC-USAS2-L8e, Руководство пользователя

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AOC-USAS2-L8i/L8e Add-on Card User’s Manual
4-6
Media Verification
The Integrated RAID firmware supports a background media verification feature that
runs at regular intervals when the mirrored volume is in optimal state. If the verification
command fails for any reason, the firmware reads the other disk’s data for this segment
and writes it to the failing disk in an attempt to refresh the data. The firmware
periodically writes the current media verification logical block address to nonvolatile
memory so the media verification can continue approximately where it left off prior to a
power cycle.
Disk Write Caching
By default, the Integrated RAID firmware disables disk write caching for mirrored
volumes. It does this to assure that the write journal entry stored in non-volatile static
RAM (NVSRAM) is always valid. If disk write caching were enabled (not recommended),
the disk write log could be invalid.
NVSRAM Usage
The Integrated RAID firmware requires at least a 32-KB NVSRAM to perform write
journaling for mirrored volumes on LSI SAS2 controllers. The NVSRAM also preserves
configuration information across reboots. The firmware uses write journaling to verify
that the disks in the mirrored volume are synchronized with each other.
Background Initialization
Background initialization (BGI) is the process of copying data from primary to secondary
disks in a mirrored volume. The Integrated RAID firmware starts BGI automatically as a
background task when it creates a volume. The volume remains in Optimal state while
BGI is in progress.
Consistency Check
A consistency check is the process of reading data from primary and secondary disks in
a mirrored volume and comparing it to make sure it is identical. You can use the SAS2
BIOS Configuration Utility to start a consistency check on a mirrored volume.
Make Data Consistent
Make data consistent (MDC) is an optional background task similar to a consistency
check. If enabled, the Integrated RAID firmware starts MDC automatically when you
move a redundant volume from one SAS controller to another SAS controller. MDC
verifies that data on the primary and secondary disks is the same.