Addonics Technologies R14HPCCES manual RAID 5 Stripe set with striped parity, Clone Mirror set

RAID 5 (Stripe set with striped parity)

Number of drives: at least 3

Unit capacity: size of one member times number of members minus one.

Spares: yes

Fault tolerance: can withstand the loss of one drive without losing data. RAID 5 works by striping entire I/O blocks across all members of the set, with each member taking turns carrying parity data computed by the Port Multi- plier. In the event of failure, the missing information can be calculated using the parity information.

CLONE (Mirror set)

Number of drives: at least 2

Unit capacity: size of one member.

Spares: yes

Fault tolerance: can withstand the loss of any number of drives without losing data as long as at least one complete member remains online. CLONE mode works the same way as RAID 1, by maintaining a complete copy of the entire set of data on each drive.

LARGE (Spanned set)

Number of drives: at least 2

Unit capacity: 100% of all drives together regardless of differences in size

Spares: no

Fault tolerance: cannot withstand the loss of any drives without losing data. However, some data may be recovered as long as the drive(s) carrying the file system data (boot record, directory, etc.) remain online. LARGE mode is neither a RAID nor is it a JBOD. It works by declaring the sum of all available space of the member drives as a single unit, without striping the data. As each member is filled, new data is stored on the next.

Notes about Spare Drives

If EZ mode is disabled (SW1:2 ON), all individual drives not configured as array members will be offered to the host adapter as separate units.

To create an array with one or more spares, set or modify the RAID mode while the spares are disconnected from the Port Multiplier. When EZ mode is enabled (SW1:2 OFF), individual drives connected when an array is present are considered spare. Spare drives must be equal to or larger in size than the smallest member. When any type of array is defined, individual units will be considered spare.

RAID 0 and LARGE arrays are not fault-tolerant and spare drives will not be useful; therefore, disabling EZ for these arrays is recommended. When a spare drive is present and a fault-tolerant RAID (1, 10, 3, or 5) is defined, EZ mode will automatically rebuild any available spares into the array to replace a failed member.

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