Adaptec MAN-00005-UG, Installation And User Manual

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214 Spheras Storage Director Installation and User Guide
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Disk performance
The controller makes the RAID implementation and the disks’ physical configuration transparent to the host operating
system. This means the host operating system drivers and software utilities are unchanged, regardless of the RAID level
selected.
B.2 RAID Levels
Selecting the proper RAID level for a specific data storage application requires consideration is given to the benefits of
each technique.
RAID 0: Striping
RAID 1: Mirroring
RAID 3: Striping with parity on one drive
RAID 5: Striping with parity across all drives
RAID 0+1: Mirroring and Striping
JBOD: Single drive control
RAID 0: Striping
The controller stripes data across multiple drives
With Spanning = RAID 00
Benefits: Very high data throughput, especially for large files.
Drawbacks: Does not deliver any fault tolerance. If any drive in the array fails, all data is lost.
Uses: Intended for non-critical data requiring high performance.
Drives: Minimum, 2. Maximum, 16.
Fault Tolerance: No.
B.2.1 RAID 1: Mirroring
The controller duplicates data from one drive to another.
With Spanning = RAID 10
Benefits: Provides 100% data redundancy. Should one drive fail, the controller simply switches reads and
writes to the other drive.
Drawbacks: Requires two drives for the storage space of one drive. While a controller is rebuilding a drive, users
will experience reduced performance if they try to read or write data to the array.
Uses: When array availability is most important.
Drives: Minimum, 2. Maximum, 2.
Fault Tolerance: Yes
B.2.2 RAID 3: Striping with Parity
RAID Level 3 provides redundant information in the form of parity to a parallel access striped array, permitting
regeneration and rebuilding in the event of a disk failure. One stripe of parity protects corresponding stripes of data on
the remaining disks.