Users guide

Intel® RAID Software User Guide 20
2.3.2 Maximizing Performance
A RAID disk subsystem improves I/O performance. The RAID array appears to the host
computer as a single storage unit or as multiple virtual units. I/O is faster because drives
can be accessed simultaneously. Table 10 describes the performance for each RAID level.
Table 10. RAID Levels and Performance
5 Combines distributed parity with disk striping. Parity provides redundancy for one drive
failure without duplicating the contents of entire disk drives. If a drive fails, the RAID
controller uses the parity data to reconstruct all missing information. In RAID 5, this
method is applied to the entire drive or stripes across all disk drives in an array. Using
distributed parity, RAID 5 offers fault tolerance with limited overhead.
6 Combines distributed parity with disk striping. RAID 6
can sustain two drive failures and
still maintain data integrity. Parity provides redundancy for two drive failures without
duplicating the contents of entire disk drives. If a drive fails, the RAID controller uses the
parity data to reconstruct all missing information. In RAID 6, this method is applied to
entire drives or stripes across all drives in an array. Using distributed parity, RAID 6
offers fault tolerance with limited overhead.
10 Provides complete data redundancy using striping across spanned RAID 1 arrays.
RAID 10
works well for any environment that requires the 100 percent redundancy
offered by mirrored arrays. RAID 10 can sustain a drive failure in each mirrored array
and maintain drive integrity.
50 Provides data redundancy using distributed parity a
cross spanned RAID 5 arrays. RAID
50 includes both parity and disk striping across multiple drives. If a drive fails, the RAID
controller uses the parity data to recreate all missing information. RAID 50 can sustain
one drive failure per RAID 5 array and still maintain data integrity.
60 Provides data redundancy using distributed parity across spanned RAID 6 arrays. RAID
60 can sustain two drive failures per RAID 6 array and still maintain data integrity. It
provides the highest level of protection against drive failures of all of the RAID levels.
RAID 60 includes both parity and disk striping across multiple drives. If a drive fails, the
RAID controller uses the parity data to recreate all missing information.
RAID
L
evel
Fault Tolerance
RAID
Level
Performance
0 RAID 0 (striping) offers the best performance o
f any RAID level. RAID 0 breaks up data
into smaller blocks, then writes a block to each drive in the array. Disk striping writes
data across multiple drives instead of just one drive. It involves partitioning each drive
storage space into stripes that can vary in size from 8 KB to 128 KB. These stripes are
interleaved in a repeated sequential manner. Disk striping enhances performance
because multiple drives are accessed simultaneously.
1 or
IME
With RAID 1 or IME (mirroring), each drive in the system must be duplicated, which
re
quires more time and resources than striping. Performance is impaired during drive
rebuilds.