240Chapter M - GDT User's ManualM. GDTSETUP in DetailAfter having explained in chapter C, Quick-Setup just a few of the GDTSETUP procedures, weshall now have a more detailed look at GDTSETUP, showing nearly all available GDT SETUPscreens with additional explanations, if necessary. The controllers of the GDT-Series areavailable with two types of firmware, each with a different performance level. These fir m-wares are either already installed on the controller upon delivery, or they can be addedlater as an upgrade: RAIDYNE upgrade for GDT controller without RAID 4/5.- Standard Firmware. In addition to simple controlling functions regarding SCSI harddisks or removable hard disk drives, this version allows disk chaining (several drivescan be linked in order to form a single "large" drive), and the configuration of diskarrays of the types data striping (RAID 0) and disk mirroring/duplexing (RAID 1).- RAIDYNE Firmware. In addition to disk chaining, RAID 0 and RAID 1, RAIDYNE al-lows you to install and control disk arrays of the types RAID 4 (data striping withdedicated parity drive) and RAID 5 (data striping with distributed parity).RAIDYNE is the name of the ICP disk array operating system for controllers of the GDT-Series. Unlike pure software solutions such as, for example, Chantal, corelRAID,RAIDIΩN/RAIDware from Micropolis, etc. RAIDYNE is entirely independent of the host o p-erating system, and can therefore be accessed under MS-DOS, Windows, OS/2, SCO-UNIX,Interactive UNIX, Novell NetWare, etc.. No special RAID drivers are needed. The integrationof a RAID Disk Array into the host operating system is carried out with the same driversused for the integration of a single SCSI hard disk. All GDT controllers are equipped withhardware which is particularly well suited for disk arrays. RAIDYNE uses this hardware withextreme efficiency and therefore allows you to configure disk arrays that do not load thehost computer. (All software RAID solutions more or less reduce the overall performance ofthe host computer.). Depending on the host operating system used, RAIDYNE allows analmost complete parallel processing of all disk I/Os.M.1 The three Levels of Hierarchy in GDT FirmwareAll three GDT firmware versions (Entry, Standard and RAIDYNE) know three fundamentallevels of hierarchy. Each level has its "own drives" ( = components). The basic rule is:To build up a ìdriveì on a given level of hierarchy, the ìdrivesì of the nextlower level of hierarchy are used as components.Level 1:Physical SCSI drives = hard disks, removable hard disks, some MO drives (also see sectionC.5) are located on the lowest level. The GDT firmware refers to these drives as disks. Theyare the basic components of all "drive constructions" you can set up. However, before theycan be used by the firmware, these disks must be "prepared", a procedure we call Initialisa-tion. During this initialisation each disk receives information which allows a univocal iden-tification even if the SCSI-ID or the controller are exchanged. For reasons of data cohe r-ency, this information is extremely important for any drive construction consisting of morethan one physical drive.Level 2:On the next higher level are the cache drives. Cache drives are logical constructions con-sisting of one or more disks. If a cache drive consists of several disks we refer to it as a
