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MaxAttach NAS 6000 Administration Guide
RAID Fault Tolerance Characteristics
Table #3 - RAID Level Availability & Fault Tolerance Characteristics
RAID
Level
0
No fault tolerance. Data is striped across a set of multiple disks. If a disk in the set ceases to function, all data
contained on the set of disks is lost. (If fault tolerance is needed, this configuration is not recommended). Excellent
for all types of I/O activity.
00
Spanned RAID 0
1
Mirrored fault tolerance. Data is written to one disk, and then the same data is written to another disk. If either disks
fails, the other one in the pair is automatically used to store and retrieve the data. Excellent for write-intensive
applications
10
Spanned RAID 1
3
Striped fault tolerance with dedicated drive parity. Data and parity are striped across a set of multiple (at least three)
drives. If any of the drives fail, the data (or parity) information from the failed drive is computed from the information
from the remaining drives.
30
Spanned RAID 3
5
Striped fault tolerance. Data and parity are striped across a set of multiple (at least three) drives. If any of the drives
fail, the data (or parity) information from the failed drive is computed from the information from the remaining drives.
Excellent for sequential or random reads and sequential writes
50
Spanned RAID 5
0+1
Mirrored and striped fault tolerance. Data and parity information is striped across multiple drives and written to a
mirrored set of drives. This arrangement can survive multiple drive failures and continue to operate.
0+1+0
Spanned RAID 0+1
JBOD
Just a Bunch of Disks. JBOD offers no redundancy and is not recommended for applications requiring fault tolerance.
RAID and Obtaining Maximum Performance
To see the advantages of the RAID levels as they apply to performance, see the table
below.
Table #4 - RAID Level Access Profile Characteristics
RAID Level
0
Excellent for all types of I/O activity.
1
Excellent for write-intensive applications.
3
Good for sequential or random reads and sequential writes.
5
Excellent for sequential or random reads and sequential writes.
0+1
Excellent for write-intensive applications.
JBOD
Mimics normal, individual disk performance characteristics.
Chapter #11 - Appendix - Disk Array RAID Concepts
11/07/01 -- Revision 2.0.03A
Availability & Fault Tolerance Characteristics
Access Profile Characteristics
Chapter #11 - Appendix - Disk Array RAID Concepts
RAID Fault Tolerance Characteristics
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