IBM ServeRAID M5210, Руководство пользователя

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ServeRAID M5210 SAS/SATA Controller for IBM System x User’s Guide
July 2014 Chapter 1: Overview
Configuration Scenarios
RAID 0 uses striping to provide high data throughput, especially for large files in an environment that does not require
fault tolerance.
RAID 1 uses mirroring so that data written to one drive is simultaneously written to another drive. This is good for
small databases or other applications that require small capacity but complete data redundancy.
RAID 5 uses disk striping and parity data across all drives (distributed parity) to provide high data throughput,
especially for small random access.
RAID 6 uses distributed parity, with two independent parity blocks per stripe, and disk striping. A RAID 6 virtual drive
can survive the loss of two drives without losing data. A RAID 6 drive group, which requires a minimum of three drives,
is similar to a RAID 5 drive group. Blocks of data and parity information are written across all drives. The parity
information is used to recover the data if one or two drives fail in the drive group.
RAID 10, a combination of RAID 0 and RAID 1, consists of striped data across mirrored spans. A RAID 10 drive group is
a spanned drive group that creates a striped set from a series of mirrored drives. RAID 10 allows a maximum of eight
spans. You must use an even number of drives in each RAID virtual drive in the span. The RAID 1 virtual drives must
have the same stripe size. RAID 10 provides high data throughput and complete data redundancy but uses a larger
number of spans.
RAID 50, a combination of RAID 0 and RAID 5, uses distributed parity and disk striping. A RAID 50 drive group is a
spanned drive group in which data is striped across multiple RAID 5 drive groups. RAID 50 works best with data that
requires high reliability, high request rates, high data transfers, and medium-to-large capacity.
RAID 60, a combination of RAID 0 and RAID 6, uses distributed parity, with two independent parity blocks per stripe in
each RAID set, and disk striping. A RAID 60 virtual drive can survive the loss of two drives in each of the RAID 6 sets
without losing data. It works best with data that requires high reliability, high request rates, high data transfers, and
medium-to-large capacity.
1.3 Configuration Scenarios
There are two main scenarios in which you can use this ServeRAID controller:

Low-end, internal SATA configuration: In this configuration, use the ServeRAID controller as a high-end SATA
compatible controller that connects to several SATA disks. This type of configuration is mostly for low-end or entry
level servers. Enclosure management is provided through out-of-band I2C bus. Side bands of both types of
internal SAS connectors support the SFF-8485 and SFF-8448 (SGPIO) interface.

Midrange, internal SAS configuration: This configuration is like the internal SATA configuration, but with high-end
disks. This type of configuration is more suitable for low-range to midrange servers.
The following figure shows a direct-connect configuration. The Inter-IC (I2C) interface communicates with peripherals.
The external memory bus provides a 32-bit memory bus, parity checking, and chip select signals for pipelined
synchronous burst static random access memory (PSBRAM), nonvolatile static random access memory (NVSRAM), and
Flash ROM.
NOTE Having virtual drives of different RAID levels, such as RAID 0 and RAID 5, in the same drive group is not
allowed. For example, if an existing RAID 5 virtual drive is created out of partial space in an array, the next
virtual drive in the array has to be RAID 5 only.