Summary Of Raid Levels - Lenovo ServeRAID M5110 User Manual

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Summary of RAID Levels

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RAID levels describe a system for ensuring the availability and
redundancy of data stored on large disk subsystems.
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 and the total number of drives must be divisible by 4 in each
RAID 10 drive group 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
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