+Bad Block

A small portion of a hard drive that, due to defect, can't hold data. SATA RAID units often contain technology which diagnoses and corrects bad blocks before they impact RAID array performance.

+Cache, Cache Memory

The removable memory modules in a RAID system which are used to provide fast retrieval of frequently accessed data, speeding operations. Usually provided by RAM chips.

+Capacity, Storage Capacity

The amount of data a RAID unit can provide, usually measured in Gigabytes or Terabytes. A 16 bay RAID with 400Gb drives has a raw storage of 6.4 Terabytes. However, its formatted capacity is only about 6Tb. RAID levels also affect data storage capacity. RAID 5 costs the user the capacity of one drive, RAID 6 two drives.

+Cluster, Server Cluster

A group of computer servers, terminals or workstations attached to a common RAID, or a networked group of servers with attached storage. A cluster preserves operational integrity by minimizing downtime. RaidWeb SATA RAID & IDE RAID have dual hosts and are server cluster ready.

+Cold Swap

Replacement of a hard drive, fan, power supply, etc. when the RAID is powered off, or a hard drive kept ready in case of an array hard drive failure. All RaidWeb units support hot swap-no power down necessary.

+Data Transfer Rate

The speed at which information can be transferred to or from a RAID, usually measured in Megabytes per second (Mb/S). Many factors affect data transfer, including interface (SCSI vs. Fibre), speed of hard drives, and much more. Additionally, read and write speeds under different operations may vary greatly.

+Direct Attached Storage (DAS)

A term that describes the direct attachment of a RAID device to a server, workstation, or terminal.

+Disk Array

Common name for a RAID unit. A term for a unit that groups hard drives (sometimes called striping) to provide increased storage capacity, speed and data security.

+Disk Cloning

A feature on Arena SATA RAID units that determines the optimum time for the system to begin cloning a failing drive to a system hot spare disk. The cloned disk can automatically take over array functionality, eliminating the degraded performance during rebuilds.

+Disk Self Test

A feature on Arena SATA RAID that automatically tests the health of installed hard drives. DST performs write tests, servo analysis, & read scan tests; the test results are then displayed on the LCD and hyper terminal outputs.

+Disk Scrubbing

A feature on Arena SATA RAID that uses idle time to test disks, and if a sector is found to be corrupted, regenerates data from other RAID member disks and writes it to an uncorrupted sector. DS prevents the possibility of having multiple corrupted sectors in a single stripe, which is one of the main causes of data loss.

+Disk Striping

A RAID process that spreads data over multiple disks in an array. Most RAID levels employ some form of striping to increase data integrity in event of failure.