Dell PowerEdge RAID Controller H700 - Manual (Page 165)

Glossary 165
M
MB
Megabyte(s). The term megabyte means 1,048,576 bytes (2^20 bytes); however,
when referring to disk storage, the term is often rounded to mean 1,000,000
bytes.
Mirroring
The process of providing complete redundancy using two physical disks,
by maintaining an exact copy of one physical disk’s data on the
second physical disk. If one physical disk fails, the contents of the other
physical disk can be used to maintain the integrity of the system and to
rebuild the failed physical disk.
N
No Read-Ahead
No read ahead is a cache read policy. If you select No Read-Ahead in the BIOS
Configuration Utility, the controller does not read sequentially ahead of
requested data and store the additional data in cache memory, anticipating that
the data is needed soon. No Read-Ahead is most effective when accessing
random data.
Non-Redundant Virtual Disk
A non-redundant virtual disk is one which does not have redundant data on
physical disks that can be used to rebuild a failed physical disk. A RAID 0 virtual
disk is a non redundant virtual disk and consists of data striped across the
physical disks, without disk mirroring or parity to provide redundancy. This
provides for high data throughput but offers no protection in case of a physical
disk failure.
NVRAM
Non-volatile Random Access Memory. A storage system that does not lose the
data stored on it when power is removed. NVRAM is used to store configuration
data on the RAID controller.
PERC7.2_UG.book Page 165 Thursday, March 3, 2011 2:14 PM