Get acquainted with a few commonly used words and terms:

A B C D E F H I J L M N O P R S T U V W

3ware Definitions for Key Terms

ACCESS TIME
The interval between the time a request is made by the system and the time the data is available from the drive. Time includes the seek time, rotational latency, and command processing overhead time.

BAD BLOCK
A block (usually the size of a sector) that cannot reliably hold data due to a physical flaw or damaged format markings.

CACHE
High-speed RAM used as a buffer between the CPU and a hard drive. Since the CPU can get information more quickly from the cache than from the main memory, the cache usually contains information that is used by the system.

DEGRADED MODE
The mode of operation of a redundant array in which in can continue to be accessed after a member drive has failed. In short, the array is functional but not fault-tolerant.

EEPROM
Electrically Erasable Programmable Read Only Memory. These devices can be erased instantly.

FAST SCSI
SCSI-1 performance enhancement that increased the maximum synchronous data transfer rate on the SCSI bus from 5 MHz to 10 MHz. This provides a transfer speed of 10MB/sec for an 8-bit bus and 20MB/sec for a 16-bit bus.

HOST
A microcomputer in which a host adapter is installed. The host bus adapter provides the host computer access to the peripheral bus.

IDE (Integrated Drive Electronics)
A disk drive interface that incorporates the drive controller into the drive electronics. IDE drives are used in IBM-compatible computers. Also known as AT.

JBOD
Just a bunch of drives. Refers to a rank of disks without data redundancy or striping.

LATENCY
The time required to access data not including the actual transfer time. Generally, the lower the latency time, the greater the access speed.

MICROPROCESSOR - BASED ARRAY CONTROLLER
An array controller in which all management functions are performed by an on-board microprocessor (for example, the Intel i960). Hardware arrays offer better performance than software-based RAID.

NARROW SCSI DEVICE
An 8-bit SCSI device.

OVERHEAD
Command overhead refers to the processing time required by the controller, host adapter, or drive prior to the execution of a command. Lower command overhead yields higher drive performance. Disk overhead refers to the space required for non-data information such as servo data. Disk overhead often accounts for about ten percent of drive capacity. Lower disk overhead yields greater disk capacity.

PARITY
A method of generating redundant information in RAID levels 2, 3, 4 and 5 to reconstruct flawed or missing data sectors within an array.

RAID
RAID, redundant array of inexpensive disks, is the technology that gives users the option of using additional drives to improve performance and/or add redundancy to their storage system within their workstations or servers. 3ware's Escalade™ controllers can be configured in a RAID-0 (striping) or RAID-1 (mirroring).

SCAM (SCSI Configures Auto Magically)
This is also known as Plug and Play for SCSI. Using this specification, the SCSI host adapter is able to automatically select the SCSI ID of itself and attached SCSI devices. It can also enable/disable termination as required to properly terminate the SCSI bus. This is an attempt to make SCSI easier to use, since the user no longer has to worry about setting SCSI ID jumpers or SCSI bus termination.

TAGGED QUEUING
A feature of SCSI-2 and SCSI-3 protocols that allow SCSI commands to be executed out of order.

ULTRASCSI
A method that enables very fast data transfer rates on the SCSI bus. The maximum UltraSCSI data transfer rates are 20 MB/second (40 MB/second for Wide SCSI host adapters).

VESA (Video Electronics Standards Association)
The association that sets standards in all areas of graphics and video technology.

WARM-SWAP
The ability to remove and replace a disk drive while the power is on. All bus activity must be paused to maintain data integrity during removal or replacement.

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