3Ware 9550SXU-16ML User Guide - Page 245

„ Remove a unit. The process of making a unit unavailable to the controller and the operating system. After a unit is removed it can be hot swapped out of the system.This is sometimes referred to as exporting a unit. „ RLM (RAID Level Migration). The process of using an existing unit of one or more drives and converting it to a new RAID type without having to delete the original unit. For example, converting a single disk to a mirrored disk or converting a RAID 0 unit to a RAID 5 unit. „ Self-test. A test that can be performed on a scheduled basis. Available self-tests include Upgrade UDMA mode and Check SMART Thresholds. „ Stagger time. The delay between drive groups that will spin up, at one time, on a particular controller. (9000 series controllers only) „ Stripe size. The size of the data written to each disk drive in RAID unit levels that support striping. The size of stripes can be set for a given unit during configuration. In general, smaller stripe sizes are better for sequential I/O, such as video, and larger strip sizes are better for random I/O (such as databases). The stripe size is user-configurable at 64KB, 128KB, or 256KB. This stripe size is sometimes referred as a a "minor" stripe size. A major stripe size is equal to the minor stripe size times the number of disks in the unit. „ Striping. The process of breaking up files into smaller sizes and distributing the data amongst two or more drives. Since smaller amounts of data are written to multiple disk drives simultaneously, this results in an increase in performance. Striping occurs in RAID 0, 5, 10 and 50. „ Subunit. A logical unit of storage that is part of another unit. For example, the mirrored pairs (RAID 1) in a RAID 10 unit are subunits of the RAID 10 unit. „ UDMA mode. UDMA mode is a protocol that supports bursting data up to 133 MB/sec with PATA disk drives and 1.5Gb/sec and 3.0 Gb/sec with SATA disk drives. „ Unit ID. A unique identifier for a specific unit in a system. „ Unit Number. The SCSI number, or channel number, of a particular unit. „ Unit. A logical unit of storage, which the operating system treats as a single drive. A unit may consist of a single drive or several drives. Also known as an array. „ Verify. A process that confirms the validity of the redundant data in a redundant unit. For a RAID 1 and RAID 10 unit, a verify will compare the data of one mirror with the other. For RAID 5 and RAID 50, a verify will calculate RAID 5 parity and compare it to what is written on the disk drive. www.3ware.com 235