HP Smart Array Controller technology, 4th edition

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RAID 6
RAID 6 protects against failure of any two drives. It requires a minimum of four drives, but only two are
available for data. RAID 6 can tolerate multiple simultaneous drive failures without downtime or data loss. It
is ideal for applications requiring large logical volumes, because it can safely protect a single volume of up
to 56 disk drives. RAID 6 also offers lower implementation costs and greater usable capacity per U than
RAID 1.
RAID 60
RAID 60 (RAID 6+0) is a nested RAID method that uses RAID 0 block-level striping across multiple RAID 6
arrays with dual distributed parity. RAID 60 lets you split RAID storage across multiple external boxes. It
requires a minimum of eight drives, but only four are available for data.
Advanced Capacity Expansion (ACE)
Advanced Capacity Expansion complements the conventional capacity expansion feature of Smart Array
controllers by letting you perform two new operations to either shrink or move existing arrays.
The Shrink Array operation allows customers to remove drives from an existing array. The Move Array
operation allows you to transfer the contents of a disk array from one set of physical drives to a second set
of physical drives.
Mirror splitting and recombining
There are two methods for safely breaking a RAID 1+0 mirror and rebuilding drives. The first method uses
the ACU. The ACU splits an array that consists of one or more RAID 1+0 logical drives into two identical
new arrays consisting of RAID 0 logical drives. The other option is a manual method, in which the volumes
remain in their original RAID 1 or RAID 1+0 configurations after the split. Using the ACU does not require
splitting other arrays attached to the controller at the same time. This functionality is useful when replicating
a configuration or building a backup before performing a risky operation.
The Array Configuration Utility will show the Split Mirror task as an available option only under all of the
following conditions:
 The version of ACU and the selected controller support the action
 The server is offline
 Any applicable SAAP keys have been installed
Drive erase
Securely sanitizing disk drives involves completely overwriting the drive data at the lowest level, below the
OS file system and partition tables. With SAS and SATA drives, this means overwriting all of the logical
blocks on the drive. HP Smart Array controllers with SAAP include an integrated Erase Drive feature that
can erase data without installing additional software. The Smart Array Erase Drive function is available
through the ACU for any logical or physical drive in an array.
The Erase Drive function operates by writing zeroes to every logical block on the logical or physical drive.
This overwrites all file contents as well as the metadata, including all RAID controller, partition, and file
system metadata. At a simplified level, erasing a drive is a serial write process, because the average
sequential write throughput of the drive governs the speed. As a result, a drive erase can take several hours
to complete on a moderate size drive such as a 500 GB midline SATA drive.