Glossary

3DM2™ Online Help

Glossary

| 3DM2. 3ware Disk Manager. The 3ware disk manager is a web-based graphical user interface that can be used to view, maintain, and manage 3ware controllers, disks, and units.

| 3ware. Named after the 3 computer wares: hardware, software and firmware. A leading brand of high-performance, high-capacity Serial ATA (SATA) and SAS (Serial Attached SCSI) RAID storage solutions.

| A-Chip. AccelerATA chip. Automated data ports to handle asynchronous SATA or SAS disk drive interface.

| Array. One or more disk drives that appear to the operating system as a single unit. Within 3ware software, arrays are typically referred to as units.

| Array Roaming. The process of swapping out or adding in a configured unit without having to shut down the system. This is useful if you need to move the unit to another controller.

| Auto-Verify. A unit policy that automates the verify process. When enabled, it performs verifies based on the Verify Schedule. It has two modes, Advanced, which has up to seven scheduling slots per week, or Basic, which has one.

| Background rebuild rate. The rate at which a particular controller initializes, rebuilds, and verifies redundant units (RAID 1, RAID 5, RAID 6, RAID 10, RAID 50).

| Boot volume size. The size to be assigned to volume 0 when creating a unit through 3BM or CLI on a PC machine. Note that the resulting volume does not have to be used as a boot volume. However, if the operating system is installed on the unit, it is installed in volume 0.

| Cache. See Read Cache and Write Cache.

| Carve size. The size over which a unit will be divided into volumes, if auto-carving is enabled.

| CLI. Command Line Interface. The 3ware CLI is a text program, rather than a GUI (graphical user interface). It has the same functionality as 3DM2, and can be used to view, maintain, and manage 3ware controllers, disks, and units.

| Configuration. The RAID level set for a unit.

| Controller. The physical card from 3ware that you insert into a computer system and connect to your disk drives or enclosure. The controller contains firmware that provides RAID functionality. 3ware makes a number of different models of SATA RAID controllers.

| Controller ID number. Unique number assigned to every 3ware controller in a system, starting with zero.

| Create an array. The process of selecting individual disk drives and selecting a RAID level. The array will appear to the operating system as a single unit. Overwrites any existing unit configuration data on the drives. Note that in 3ware software tools, arrays are referred to as units.

| DCB. Disk configuration block. This is 3ware proprietary RAID table information that is written to disk drives that are in a RAID unit or single disk. The DCB includes information on the unit type, unit members, RAID level, and other important RAID information.

| Delete an array. Deleting an array (or unit) is the process of returning the drives in a unit to individual drives. This erases the DCB information from the drives and deletes any data that was on them. When a unit is deleted from a controller, it is sometimes referred to as being “destroyed.” If you want to remove a unit without deleting the data on it, do not delete it; instead use the Remove feature in 3DM2, and then physically remove the drives.

| Destroying. Same as deleting a unit.

| Degraded unit. A redundant unit that contains a drive that has failed.

| Disk roaming. When moving a unit from one controller to another, refers to putting disks back in a different order than they initially occupied, without harm to the data.

| Distributed parity. Parity (error correction code) data is distributed across several drives in RAID 5, RAID 6, and RAID 50 configurations. Distributing parity data across drives provides both protection of data and good performance.

| Drive ID. A unique identifier for a specific drive in a system. Also called a port ID.

| Drive Number. The SCSI number, or channel number, of a particular drive.

| ECC. Error correction code. ECC Errors are grown defects that have occurred on a drive since it was last read.

| ECC Error policy. Determines whether an error detected during a rebuild stops the rebuild or whether the rebuild can continue in spite of the error. Specified by the Ignore ECC (Continue on Source Error When Rebuilding) unit policy.

| Enclosure. An enclosure houses drives and a backplane. The backplane may have an expander.

| Expander. Expanders are simple switches in enclosures that provide connectivity between the 3ware 9750 RAID controller and the other devices in the SAS domain. Expanders allow one phy to connect to multiple drives.

| Export a unit. To remove the association of a unit with a controller. Does not affect the data on the drives. Used for array roaming, when you want to swap out a unit without powering down the system, and move the unit to another controller. Compare to Delete, which erases all unit configuration information from the drive.

| Exportable unit or drive. In 3BM (BIOS), exportable units and drives are those that will be available to the operating system when you boot your computer.

| Fault tolerant. A RAID unit which provides the ability to recover from a failed drive, either because the data is duplicated (as when drives are mirrored) or because of error checking (as in a RAID 5 unit).

| Firmware. Computer programming instructions that are stored in a read-only memory on the controller rather than being implemented through software.

| Grown defect. Defects that arise on a disk from daily use.

| Hot spare. A drive that is available, online, and designated as a spare. When a drive fails in a redundant unit, causing the unit to become degraded, a hot spare can replace the failed drive automatically and the unit will be rebuilt.

| Hot swapping. The process of removing a disk drive from the system while the power is on. Hot swapping can be used to remove units with data on them, when they are installed in hot swap bays. Hot swapping can also be used to remove and replaced failed drives when a hot swap bay is used.

| Import a unit. Attach a set of disk drives with an existing configuration to a controller and make the controller aware of the unit. Does not affect the data on the drives.

| Initialize. For 3ware SATA RAID controllers, initialize means to put the redundant data on the drives of redundant units into a known state so that data can be recovered in the event of a disk drive failure. For RAID 1 and 10, initialization copies the data from the lower port to the higher port. For RAID 5, 6, and 50, initialization calculates the RAID 5 parity and writes it to disk (background initialization). This is sometimes referred to as resynching, and does not erase user data. Note: If foreground initialization is done before the operating system has loaded, zeroes are written to all of the drives in the unit. This process, done through the 3ware BIOS, does erase existing data.

| Logical Units. This term is used in the 3ware CLI. It is usually shortened to “units.” These are block devices presented to the operating system. A logical unit can be a one-tier, two-tier, or three-tier arrangement. Single logical units are examples of one-tier units. RAID 1, RAID 5, and RAID 6 are examples of two-tier units and as such will have sub-units. RAID 10 and RAID 50 are examples of three-tier units and as such will have sub-sub-units.

| JBOD. An unconfigured single drive. The acronym is derived from “just a bunch of disks.” Note that earlier versions of the 3ware RAID controller exported JBODs to the OS. This is no longer supported. Individual drives should be configured as Single Disks in order to be made available to the OS.

| Migration. The process of changing the characteristics of a unit. The change can be to expand the capacity of the unit (OCE), change the stripe size of the unit, change the unit from redundant to non-redundant, change the unit from non-redundant to redundant, and to change the unit from one type of redundant unit to another type of redundant unit (for example RAID 1 to RAID 5).

| Mirrored disk array (unit). A pair of drives on which the same data is written, so that each provides a backup for the other. If one drive fails, the data is preserved on the paired drive. Mirrored disk units include RAID 1 and RAID 10.

| NCQ (Native Command Queuing). See “Queuing”

| Non-redundant units. A disk array (unit) without fault tolerance (RAID 0 or single disk.).

| OCE (Online Capacity Expansion). The process of increasing the size of an existing RAID unit without having to create a new unit. See also migration.

| Parity. Information that the controller calculates using an exclusive OR (XOR) algorithm and writes to the disk drives in RAID 5, RAID 6, and RAID 50 units. This data can be used with the remaining user data to recover the lost data if a disk drive fails.

| PCB. Printed circuit board.

| P-Chip. PCI interface chip that connects the PCI bus to the high-speed internal bus and routes all data between the two using a packet switched fabric. There is one P-chip per controller card.

| Phy. Phys are transceivers that transmit and receive the serial data stream that flows between the controller and the drives. 3ware 9750 controllers have multiple phys. These phys are associated with virtual ports (vports) by 3ware software to establish up to 127 potential connections with the SAS or SATA hard drives.

| Phy Identifier. The ID number (0-7) assigned to each of the 8 phys on the 9750 controller.

| Port. 3ware controller models have one or many ports (typically 4, 8, 12, 16, 24, or 28). Each port can be attached to a single disk drive. On a controller with a Multi-lane serial port connector, one connector supports four ports. On 9750 series controllers, connections are made with phys and vports (virtual ports). See “phy” and “VPort”.

| Port ID. A unique identifier for a specific port in a system. Also called a drive ID.

| Queuing. SATA drives can use Native Command Queuing (NCQ) to improve performance in applications that require a lot of random access to data, such as server-type applications. When NCQ is enabled, the commands are reordered on the drive itself.

NCQ must be supported by the drive. NCQ must be turned on in both the drive and the RAID controller. By default, the RAID unit’s queue policy is disabled when creating a unit.

| RAID. Redundant array of inexpensive disks, combined into a unit (array), to increase your storage system’s performance and provide fault tolerance (protection against data loss).

| Rapid RAID Recovery. The Rapid Raid Recovery feature increases the speed with which a redundant unit can be made redundant again when a rebuild is required. It can also increase the speed of verification or initialization that may occur in the event of an unclean shutdown.

| Read Cache. Read Cache stores data from media locally on the controller to improve read access times for applications. The 3ware Read Cache feature also includes an Intelligent Mode, which enables Intelligent Read Prefetch (IRP). IRP includes a typical read-ahead caching method which is used to proactively retrieve data from media and store it locally on the controller with the anticipation that it may be requested by the host.

| Rebuild task schedule. The specification for when rebuilding, may occur, including start time and duration.

| Rebuild a unit. To generate data on a new drive after it is put into service to replace a failed drive in a fault tolerant unit (for example, RAID 1, 10, 5, 6, or 50).

| Redundancy. Duplication of data on another drive or drives, so that it is protected in the event of a drive failure.

| Remove a drive. The process of making a drive unavailable to the controller.

| 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 Check SMART Thresholds.

| Stagger time. The delay between drive groups that will spin up, at one time, on a particular controller.

| SAS. SAS (Serial Attached SCSI) is a serial communication protocol for storage devices. The SAS protocol includes support for SAS and SATA devices.

| SAS address. Each SAS device (SAS drives, controllers, and expanders) has a worldwide unique 64-bit SAS address. Also known as World Wide Number (WWN). SATA drives do not have a WWN and are identified by a VPort ID.

| SAS device. SAS devices include SAS drives, controllers, and any expanders present in the SAS domain. Each SAS device has a unique 64-bit World Wide Number (WWN). SATA drives do not have a WWN and are identified by their VPort IDs

| SAS domain. The SAS domain includes all SAS and SATA devices that are connected to the 9750 controller, either directly or through expanders.

| SES (SCSI Enclosure Services). The SES protocol allows the 9750 RAID controller to manage and report the state of the power supplies, cooling devices, displays, indicators, individual drives, and other non-SCSI elements installed in an enclosure.

| 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. The stripe size is user-configurable at 64 KB, 128 KB, or 256 KB.

This stripe size is sometimes referred as 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, 6, 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.

| 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, RAID 6, and RAID 50, a verify will calculate RAID 5 parity and compare it to what is written on the disk drive.

| VPort. The 3ware 9750 RAID controller has 127 addresses available to assign to hard drives. These addresses are known as virtual port (vport) IDs. By using vport IDs and expanders, one controller phy can connect to multiple drives. This is in contrast to standard port connections which are one-to-one physical connections.

| Wide Port. A SAS port can consist of one or more phys. When a SAS port consists of one phy it is known as a narrow port, when it contains multiple phys it is known as a wide port. The 3ware 9750 controllers has multiple wide port connectors that contain 4 phys each. These phys can function individually, in which case each phy has its own SAS address, or the 4 phys can be banded together, in which case they share the same SAS address. A 9750 wideport can have a bandwidth of up to 12.0 Gbps for SAS 1.1 and 24 Gbps for SAS 2.0..

| WWN (World Wide Number). The unique worldwide 64-bit SAS address assigned by the manufacturer to each SAS port and expander device in the SAS domain. Many SAS drives have 2 ports and thus 2 WWNs.

| Write Cache. When write cache is enabled, data will be stored in controller cache and drive cache before the data is committed to disk. This allows the system to process multiple write commands at the same time, thus improving performance

LSI Corporation

Copyright LSI 2004-2010
To contact Support, go to http://www.lsi.com/channel/ContactUs