Avago Technologies MegaRAID Fast Path Software - Manual (Page 495)

LSI Corporation Confidential | July 2011 Page 495
MegaRAID SAS Software User Guide Appendix C: Glossary
patrol read A process that checks the drives in a storage configuration for drive errors that could
lead to drive failure and lost data. The patrol read operation can find and sometimes fix
any potential problem with drives prior to host access. This enhances overall system
performance because error recovery during a normal I/O operation might not be
necessary.
patrol read rate The user-defined rate at which patrol read operations are run on a computer system.
product info A drive property indicating the vendor-assigned model number of the drive.
product name A controller property indicating the manufacturing name of the controller.
RAID A group of multiple, independent drives that provide high performance by increasing
the number of drives used for saving and accessing data.
A RAID drive group improves input/output (I/O) performance and data availability. The
group of drives appears to the host system as a single storage unit or as multiple virtual
drives. Data throughput improves because several drives can be accessed
simultaneously. RAID configurations also improve data storage availability and fault
tolerance. Redundant RAID levels (RAID levels 1, 5, 6, 10, 50, and 60) provide data
protection.
RAID 0 Uses data striping on two or more drives to provide high data throughput, especially
for large files in an environment that requires no data redundancy.
RAID 00 Uses data striping on two or more drives in a spanned drive group to provide high data
throughput, especially for large files in an environment that requires no data
redundancy.
RAID 1 Uses data mirroring on pairs of drives so that data written to one drive is
simultaneously written to the other drive. RAID 1 works well for small databases or
other small applications that require complete data redundancy.
RAID 5 Uses data striping and parity data across three or more drives (distributed parity) to
provide high data throughput and data redundancy, especially for applications that
require random access.
RAID 6 Uses data striping and parity data across three or more drives (distributed parity) to
provide high data throughput and data redundancy, especially for applications that
require random access. RAID 6 can survive the failure of two drives.
RAID 10 A combination of RAID 0 and RAID 1 that uses data striping across two mirrored drive
groups. It provides high data throughput and complete data redundancy.
RAID 50 A combination of RAID 0 and RAID 5 that uses data striping across two drive groups
with parity data. It provides high data throughput and complete data redundancy.
RAID 60 A combination of RAID 0 and RAID 6 that uses data striping across two drive groups
with parity data. It provides high data throughput and complete data redundancy.
RAID 60 can survive the failure of two drives in each RAID set in the spanned drive
group.
RAID level A virtual drive property indicating the RAID level of the virtual drive.
LSI SAS RAID controllers support RAID levels 0, 1, 5, 6, 10, 50, and 60.
raw capacity A drive property indicating the actual full capacity of the drive before any coercion
mode is applied to reduce the capacity.