Dell PERC 4/im - Manual (Page 4)

capacity for the IM volume. The IM firmware resynchronizes all hot-swapped disks that have been removed, even if
the identical disk is re-inserted. The IM firmware marks all hot-swapped disks as the secondary disk and marks the
other mirrored disk as the primary disk. The IM firmware resynchronizes all data from the primary disk onto the new
secondary disk.
Disk Write Caching
The IM firmware disables disk write caching. This is done to increase data integrity, so that the disk write log stored
in NVSRAM is always valid. If disk write caching is enabled (not recommended), the disk write log could be invalid.
For example, consider this case: a write I/O completes to the first physical IM drive. The duplicated write I/O remains
in the cache of the second drive. Both I/Os are reported as complete from the IM firmware, and the system is
powered off.
Please read all restrictions and disclaimers.
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