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\glossary "Active Controller Mode"
\0\p
A controller mode indicating that the controller owns logical units (LUN) and handles I/O requests from the host for those LUNs.
\p\p
(See also Redundant Controller Pair) \p

\glossary "Active/Active Controller Pair"
\0\p
Also known as dual-active. The status of a controller pair in which both controllers have specific logical units (LUN) assigned to them and handle I/O requests from the host for those LUNs.
\p\p
If one of the controllers fails, the LUNs are switched over to the other active controller.
\p\p
(See also Controller Mode) \p

\glossary "Active/Passive Controller Pair"
\0\p
The status of a controller pair in which one controller (active) owns all of the logical units (LUN) and the other controller (passive) acts as a standby.
\p\p
If the active controller fails, the passive controller becomes active and the LUNs are switched over to it. \p

\glossary "Activity Lights"
\0\p
Each drive canister in the RAID Module has an activity light that flashes when there is I/O activity (for example, read/write requests, reconstruction, etc.) to the module. This light also flashes when you use List/Locate Drives in the Configuration Application (for a specific drive group) or Locate Module (for all the drives in the module).
\p\p
Some RAID Modules may also have a summary activity light that flashes whenever there is I/O activity to the module. You can flash this light using Locate Module to identify a specific RAID Module. \p

\glossary "ASC/ASCQ Code"
\0\p
An ASC is a SCSI Additional Sense Code and an ASCQ is an ASC Qualifier. ASC/ASCQ codes are sent by the controller to provide further information about error messages displayed in Message Log of the Status Application. \p

\glossary "Bootware"
\0\p
Executable code in the controller firmware for running hardware diagnostics, initializing the hardware, and uploading other controller firmware. The Maintenance/Tuning Application allows you to upgrade firmware. \p

\glossary "Cache Read Ahead"
\0\p
Also known as Prefetch. An option that allows a logical unit to prefetch data into cache for improved sequential read performance. Normally, you should not enable this option unless the selected logical units are processing a very high percentage of sequential I/O.
\p\p
You can enable this option for individual logical units using the command line utility, raidutil. \p

\glossary "Cache Without Batteries"
\0\p
An option that allows write caching to continue even if the batteries are discharged completely, not fully charged, or if there are no batteries present. If you select this option without a UPS for protection, you could lose data if a power failure occurs.
\p\p
You can enable this option when creating LUNs using the Configuration Application or later using the Maintenance/Tuning Application. \p

\glossary "Cache Memory"
\0\p
Cache memory is an area on the controller used for intermediate storage of read and write data. By using cache, you can increase system performance because the data for a read or write operation from the host may already be in the cache from a previous operation (thus the need to access the drive itself is eliminated), or the write operation is completed once it is written to the cache.
\p\p
When you create a logical unit, you can specify various caching parameters for the LUNs. If you need to change any caching parameters after LUN creation, use the Maintenance/Tuning Application. (NOTE: You can also use the command line utility, raidutil, for setting these and other more advanced caching parameters.)
\p\p
(See also Cache Without Batteries, Write Cache Mirroring, Write Caching, and Processor Memory) \p

\glossary "Channel"
\0\p
A path for the transfer of data and control information between a disk drive and a controller. Disk drives in a SCSI-Based RAID Module are identified by channel and SCSI ID. \p

\glossary "Checking Interval"
\0\p
The parameter, in minutes, for how often the background monitor checks the status of your RAID Modules. You can change the "check RAID Modules every x minutes" setting by using Options >> Log Settings in the Status Application. \p

\glossary "Configured Drive Group"
\0\p
A set of drives that have one or more logical units configured on them with the same RAID Level. Each configured drive group is designated with a number (e.g. 1, 2, 3, etc.). These drive groups are displayed by number in all applications. \p

\glossary "Controller"
\0\p
A board and firmware, located in the RAID Module, that control the I/O between the logical units and the host system. \p

\glossary "Controller Mode"
\0\p
Identifies the operating state of the controller. Applicable controller modes are active, passive, and offline. You can determine the modes of the controllers by using Module Profile. You could also see (Inaccessible) with these statuses if the RAID Module has an independent controller configuration.
\p\p
You can change a controller pair from active/passive to active/active or swap the active/passive controller using Controller Mode in the Maintenance/Tuning Application.
\p\p
(See also Active, Passive, and Offline Controller Mode; and Independent Controller Configuration) \p

\glossary "Dead Mode"
\0\p
A logical unit status occurring when two or more drives have failed in the same drive group, or one or more drives have failed in a RAID 0 drive group. All the logical units on the drive group are Dead and are no longer operating.
\p\p
This is the most serious status for a logical unit and you have lost data unless you accidentally removed the second drive and it was optimal. Use Recovery Guru in the Recovery Application to restore your drive group to Optimal status. \p

\glossary "Degraded Mode"
\0\p
A mode of operation for a RAID 1, 3, or 5 logical unit (LUN) when one drive fails in a drive group. The controller continues to function in the degraded mode because it uses the data and parity (or redundant data for RAID 1) on the drives that are still operational. This enables you to continue reading and writing to the LUN without losing data and to reconstruct the data after you replace the failed drive.
\p\p
If a hot spare drive is configured and takes over for the failed drive, the LUN remains in an Optimal status and still shows a single failed drive. \p

\glossary "Device Name"
\0\p
The software uses device addresses which are determined by the location of the subsystem hardware and can vary according to the operating system you are using.
\p\p
For example, most UNIX operating systems use a cXtXdXsX scheme, the Windows NT operating system uses a driveX scheme, and the Networked version uses an eight character scheme you defined during installation. \p

\glossary "Drive Group"
\0\p
A drive group is a physical set of drives in the RAID Module. The drive groups are defined during configuration. There are three types of drive groups:
\p\p
Unassigned drive group -- is a set of drives that has not been configured into logical units or hot spares. This drive group is only displayed in the Configuration Application.
\p\p 
Hot spare drive group -- indicates the drives that have been assigned as hot spares. This drive group is only displayed in the Configuration Application.
\p\p
Configured drive group -- is a set of drives that has been configured into one or more logical units with the same RAID Level. Each configured drive group is designated with a number (e.g. 1, 2, 3, etc.). These drive groups are displayed by number in all applications.
\p\p
Also, there are limitations on how many drives can comprise one drive group. \p

\glossary "Filter"
\0\p
A UNIX option that allows you to narrow the path parameters to specific directories, filenames, and even file extensions. Available in options such as Open Log/Save Log As in the Status Application and Save Module Profile. \p

\glossary "Firmware"
\0\p
Executable code for controller operation that resides on the controller. The Maintenance/Tuning Application allows you to upgrade firmware.
\p\p
(See also Bootware) \p

\glossary "General Message Type"
\0\p
In Message Log of the Status Application, the General type of message shows events that have a general status, such as reconstruction occurring, formatting complete messages, etc. \p

\glossary "Hardware Message Type"
\0\p
In Message Log of the Status Application, the Hardware type of message shows events that are specific to hardware. These messages are normally associated with ASC/ASCQ codes. \p

\glossary "Hot Spare"
\0\p
A hot spare is a drive containing no data that acts as a standby in case a drive fails in a RAID 1, 3, or 5 logical unit.
\p\p
The hot spare drive adds another level of redundancy to your RAID Module. If a drive fails, the hot spare takes over for the failed drive until you replace it. Once you replace the failed drive, the hot spare returns to a Spare-Stdby (standby) status.
\p\p
A hot spare drive is not dedicated to a specific drive group/LUN but instead can be used for any failed drive in the RAID Module with the same or smaller capacity. This drive group is displayed only in the Configuration Application. \p

\glossary "Hot Swap"
\0\p
The ability to remove and replace a component (controller, drive, etc.) in a RAID Module while power is applied AND data activity to and from the RAID Module continues. \p

\glossary "Inaccessible"
\0\p
You could see this status on drives, logical units (LUNs), or a controller. You see this status for drives and LUNs under two conditions:
\p\p
a. If the selected RAID Module has an independent controller configuration, this status indicates that the component is owned by the alternate controller. Inaccessible drives and LUNs cannot be accessed using the storage management software from the current host.
\p\p
b. If you have moved the RAID Module from another host machine system to one that supports fewer configured LUNs, this status indicates that the new host cannot access the LUNs marked inaccessible. For example, this could occur if the RAID Module used to be part of a host system that was able to support 32 configured LUNs, but is moved to a new host system that only supports 8 LUNs. In this case, LUNs 8-31 would be seen as Inaccessible.
\p\p
(See also Independent Controller Configuration) \p

\glossary "Independent Controller Configuration"
\0\p
Two host machines are connected to a dual-controller RAID Module. One host machine is connected by a SCSI Bus to one controller, and a second host machine is connected by another SCSI Bus to the other controller. Each host machine sees the controller and the drive groups/LUNs that it owns as independent of the other (alternate) controller. That is, each host machine acts as if it is connected to a single-controller RAID Module.
\p\p
No RDAC failover support exists for the controllers. \p

\glossary "Installation Directory"
\0\p
The directory where the files for this software were placed during the installation procedure varies according to your operating system.
\p\p
For most UNIX systems, the installation directory is /etc/raid.
\p\p
For Windows NT, you may define the installation directory as anything you want; however, the default provided at installation is \p
\\symsm
\p\p
For the Networked version, you may define the installation directory as anything you want; however, the default provided at installation is \p
\\netsymsm
\p\p
Consult the "Installation And Support Guide" for your operating system for specific information. \p

\glossary "I/O Data Path"
\0\p
Refers to the route that data travels from the system host adapter through the interface cable (either SCSI or fibre) to the controller. \p

\glossary "Location (Drive)"
\0\p
Each drive has a unique location in the RAID Module corresponding to its channel number and SCSI ID. This location information is displayed as [x,y] on screen where the channel number is always listed first. Use the location information to match it to a unique drive and to help locate it in the RAID Module. For example, [2,1] corresponds to the drive at location SCSI Channel 2 and SCSI ID 1.
\p\p
(See also SCSI Channel and SCSI ID) \p

\glossary "Log File"
\0\p
Where Message Log stores its information for all RAID Modules. You can change the default setting by using Log Settings in the Status Application. \p

\glossary "Log Size Before Notification"
\0\p
An option that provides notification when the default Message Log has reached a certain size. The default is 40K. You can change the default file or notification size using Options >> Log Settings in the Status Application. \p

\glossary "Logical Unit"
\0\p
A logical unit (LUN) is the basic structure you create on the RAID Modules to retrieve and store your data. A LUN is a set of physical drives (that is, a drive group) that have been configured into either RAID Level 0, 1, 3, or 5. Each logical unit (not the drive group) is seen by the operating system as ONE drive. \p

\glossary "LUN"
\0\p
LUN stands for logical unit number, but is often used to mean logical unit. \p

\glossary "LUN Assignment"
\0\p
A RAID Module's controllers own logical units (LUN) and handle I/O requests from the host for those LUNs.
\p\p
If a module has only one controller or an active/passive controller pair, all the LUNs are assigned to the active controller. If a module has two active controllers, the software automatically assigns the odd numbered drive groups to one controller and the even numbered drive groups to the other controller.
\p\p
You can change LUN assignment when creating LUNs using the Configuration Application or later using the Maintenance/Tuning Application.
\p\p
(See also Active Controller Mode, Active/Active Controller Pair, and Active/Passive Controller Pair) \p

\glossary "Message Types"
\0\p
You can determine which type of information the Status Application's Message Log displays by selecting List Types in the summary information screen.
\p\p
The default is to display all types of messages; however, you can limit that to one or more types, including parity, general, and hardware. \p

\glossary "Multi-Host Configuration"
\0\p
Two host machines are each connected by two SCSI Buses to both of the controllers in a RAID Module.
\p\p
With this storage management software installed on each host machine, both hosts have complete visibility of both controllers, all data paths, and all configured drive groups/LUNs in a RAID Module, plus RDAC failover support for the redundant controllers. However, in this configuration, you must use caution when performing storage management tasks that need exclusive access. Especially when creating and deleting LUNs, be sure you have only one configuration session open at a time (from only one host) or the operations could fail. 
\p\p
CAUTION \p
Not every operating system supports the multi-host configuration. Be sure to consult the restrictions in the operating-system specific "Installation And Support Guide." \p

\glossary "No Controller"
\0\p
A potential status shown when controller pairs are listed that normally indicates that the selected RAID Module has only one controller. This status could also indicate that the controller is no longer detected because there is a bad cable connection or the controller has been taken offline. \p

\glossary "NVSRAM File"
\0\p
This controller file comes from your Customer Services Representative and specifies certain default settings for the controller.
\p\p
In most cases, you will have to download a new NVSRAM file BEFORE upgrading controller firmware, especially if you are upgrading from one major firmware release to another (for example, from 2.03 to 2.04). You must copy the file to your host system before downloading. Then, you can use the Firmware Upgrade option (Maintenance/Tuning Application) to download the file. \p

\glossary "Offline Controller Mode"
\0\p
A controller mode indicating that the controller no longer receives I/O. A controller is usually placed offline by the RDAC Driver in response to a problem on the I/O data path. A controller can also be placed offline manually using the Manual Recovery >> Controller Pairs option in the Recovery Application. \p

\glossary "Offline Firmware Upgrade"
\0\p
Process for upgrading controller firmware that requires you to stop all I/O to the selected RAID Module. You must use this procedure for modules that have only one controller or that are using the independent controller configuration. \p

\glossary "Online Firmware Upgrade"
\0\p
Process that allows you to upgrade controller firmware while the selected RAID Module receives I/O. \p

\glossary "Parity"
\0\p
Parity is additional information stored along with the data that allows the controller to reconstruct lost data. Only RAID 3 and 5 have parity. RAID 1 uses mirroring, not parity, although you can run parity check and repair on a RAID 1 logical unit. \p

\glossary "Parity Check/Repair"
\0\p
Parity check is the process of scanning the blocks in a logical unit and checking the parity for each block.
\p\p
Parity repair is the process of correcting any parity inconsistencies found during parity check.
\p\p
A daily parity check/repair is initiated by the software on RAID 1, 3, or 5 logical units to ensure data integrity. However, this process corrects only parity errors. If the errors were caused by corrupted data, the data is still corrupted.
\p\p
You can change the time at which the check is run by using Auto Parity Settings in the Maintenance/Tuning Application. You can also initiate a manual check/repair using the Recovery Application. \p

\glossary "Parity Message Type"
\0\p
In Message Log of the Status Application, the Parity type of message shows the results of parity check/repair operations when parity inconsistencies are found and repaired. \p

\glossary "Passive Controller Mode"
\0\p
A controller mode indicating that the controller is acting as a spare. If the active controller fails, the passive controller becomes active and takes over the logical units owned by the failed controller.
\p\p
(See also Redundant Controller Pair) \p

\glossary "Processor Memory"
\0\p
Processor memory is an area on the controller used by the processor to perform RAID operations. \p

\glossary "Program Group"
\0\p
A collection of applications and files that comprise this software. Each application has an icon in the program group for selecting it. \p

\glossary "RAID"
\0\p
RAID is an acronym for Redundant Array of Independent Disks. Describes a storage solution in which part of the storage capacity is used to store redundant information about user data stored on the remainder of the storage capacity. The redundant information enables regeneration of user data if one of the disk drives in the drive group fails. \p

\glossary "RAID 0"
\0\p
Non-redundant RAID Level where data, without parity, is striped across a drive group/LUN. All drives are available for storing user data. Any single drive failure causes data loss and a logical unit status of Dead. \p

\glossary "RAID 1"
\0\p
Redundant RAID Level where identical copies of data are maintained on drive pairs, also known as mirrored pairs. Half of the drives are available for storing user data. Drive pair failure causes data loss.
\p\p
Sometimes referred to as RAID 0/1 or RAID 0+1.
\p\p
You can view mirrored pairs using List/Locate Drives (in the Configuration Application). The mirrored-pair drives are indicated by a number appearing in front of the drive location information. (For example, (1) appears in front of the first mirrored pair, (2) appears in front of the second mirrored pair. etc.) \p

\glossary "RAID 3"
\0\p
Redundant RAID Level where data and parity are striped across a drive group/LUN. One drive's worth is used for redundancy; all other drives available for storing user data. Any two-drive failure in the same drive group causes data loss. \p

\glossary "RAID 5"
\0\p
Redundant RAID Level where data and parity are striped across a drive group/LUN. One drive's worth is used for redundancy; all other drives available for storing user data. Any two-drive failure in same drive group causes data loss. \p

\glossary "RAID Level"
\0\p
Indicates the way the controller reads and writes data and parity on the drives. The controller can create RAID Level 0, 1, 3, and 5 logical units. These levels do NOT indicate any certain hierarchy or preference.
\p\p
(See also Parity) \p

\glossary "RAID Module"
\0\p
A RAID Module is defined as a set of drives and a set of controllers (single active, active/passive, or active/active) and applicable power supplies/fans. A RAID Module is what you select to perform the various RAID Tasks (such as configuring, obtaining status, recovering, etc.).
\p\p
For example, a single unit with 20 drives and two active controllers would be considered one RAID Module. If the RAID Module is a stand-alone unit, it is synonymous with the term RAID Subsystem. However, if you have a rack-mount subsystem, each unit contained in the cabinet is considered a RAID Module. Therefore, a subsystem cabinet containing three rack-mount units would be listed as three RAID Modules. \p

\glossary "RDAC"
\0\p
RDAC is an acronym for Redundant Disk Array Controller.
\p\p
(See also RDAC Driver) \p

\glossary "RDAC Driver"
\0\p
The Redundant Disk Array Controller (RDAC) Driver is part of the RAID Management software package and manages the I/O path for RAID Modules with redundant controllers. If a component fails on the I/O path (cable, controller, host adapter, etc.) that causes the host to lose communication with a controller, the driver automatically reroutes all I/O operations to the other controller.
\p\p
Consult the "Installation And Support Guide" for your operating system for specific information. \p

\glossary "Reconstruction"
\0\p
The process of using data and parity on all operational drives to regenerate the data on the drive that the controller marked as failed. Only data on a RAID 1, 3, or 5 logical unit can be reconstructed.
\p\p
(See also Reconstruction Rate) \p

\glossary "Reconstruction Rate"
\0\p
The rate defines how much processing time is allocated for reconstruction and for system performance. You can change this rate for logical units undergoing reconstruction in the Status Application or for all logical units whether or not they are reconstructing in the Maintenance/Tuning Application. \p

\glossary "Redundant Controller Pair"
\0\p
When a RAID Module has at least two controllers installed. These controller pairs are either active/active or active/passive. The redundant pair allows the RAID Module to continue operation even if one controller fails in the pair. \p

\glossary "SCSI Channel"
\0\p
A number used to identify the path for the transfer of data between a disk drive and a RAID Controller. \p

\glossary "SCSI ID"
\0\p
A number used to identify the drive on the SCSI Bus between the controller and drives (Drive-side SCSI Bus). \p

\glossary "Segment Size"
\0\p
A segment is the amount of data the controller writes on a single drive in a logical unit before writing data on the next drive. The segment size is comprised of blocks (one block equals 512 bytes). \p

\glossary "Single-Host Configuration"
\0\p
One host machine is connected by two SCSI Buses to each controller in a RAID Module. The two SCSI Buses are required for maximum RDAC failover support for redundant controllers.
\p\p
This is the recommended configuration with the storage management software installed on the host for fullest functionality and complete RDAC failover support with dual controllers. However, this configuration also supports RAID Modules that have a single-controller or dual controllers on the same SCSI Bus. You do not have complete RDAC data path protection with either of these configurations. \p

\glossary "SNMP"
\0\p
SNMP is an acronym for Simple Network Management Protocol. A feature provided for error notification that you can enable.
\p\p
For details, see the "Installation And Support Guide" for your operating system. \p

\glossary "Target"
\0\p
Also known as an NMS (Network Management Station). A remote network manager you can assign to receive trap messages using the SNMP feature. \p

\glossary "Trap"
\0\p
A SNMP message type sent to an assigned target. \p

\glossary "Unassigned Drive Group"
\0\p
Drives not yet configured into logical units for a RAID Module. The controller does not write to or monitor these drives. This drive group is displayed only in the Drive Groups area of the Configuration Application. \p

\glossary "UPS (Uninterruptible Power Supply)"
\0\p
This power supply provides battery backup in case of power failure. This is an important backup option to have for enabling caching. \p

\glossary "Write Caching"
\0\p
An option that allows write operations from the host to be stored in the controller's cache memory. 
The use of write caching increases overall performance because the data for a write operation may already be in the cache from a previous operation, thus eliminating the need to access the drive itself.
\p\p
You can enable this option when creating LUNs using the Configuration Application or later using the Maintenance/Tuning Application. \p

\glossary "Write Cache Mirroring"
\0\p
An option that allows cached data to be mirrored across two redundant controllers that have the same cache size. The data written to the cache memory of one controller is also written to the cache memory of the other controller. Therefore, if one controller fails, the other can complete all outstanding write operations.
\p\p
You can enable this option when creating LUNs using the Configuration Application or later using the Maintenance/Tuning Application. \p