HP xw4200 - Device Classes; Attach Sequence Rules by Class Priority; Additional Drive Application Notes

DRIVE INSTALLATION GUIDELINES 161
Appendix C
Device Classes
To determine the best drive attach sequence, Ultra ATA/ATAPI drives are segregated into four different
classes based on the bandwidth demands they place on an Ultra ATA controller. The most demanding
devices are in Class 1. The least demanding devices are in Class 4. The following table illustrates those
classes.
General Attach Guidelines
 The lower the device class number, the faster the device and the more bandwidth required.
 Drives installed in the Device 0 position receive the greatest possible bandwidth.
Attach Sequence Rules by Class Priority
The following table summarizes the attach sequence rule.
Additional Drive Application Notes
 When replacing a hard drive, the replacement should be of the same type (Ultra ATA 33, -66, or
-100) as that being removed to retain the same level of performance.
 When Ultra ATA and SATA hard drives are mixed in the same system, the SATA drive will become the
boot drive unless the boot order is changed in Computer Setup (F10). The default boot order on this
system prefers SATA, then Ultra ATA, then SCSI.
Table C-1
Device Classes
Class 1
Hard Drives
Class 2
High Speed Optical Drives
Class 3
Optical Storage Drives
Class 4
Magnetic Storage Drives
Ultra ATA-100
Ultra ATA-66
Ultra ATA-33
DVD
DVD-CD R/W
R/W CD-ROM
CD-ROM
LS-120
Tape
Zip
Table C-2 General Attach Sequence Rule*
Sequence Description
1 The lowest class drive—bootable hard drive recommended.
2 If only two drives, the last drive goes here; otherwise the lowest class of the remaining drives.
*If there are three or more devices, two or more of which are hard drives, two hard drives should be attached to the
primary controller first before following the General Attach Sequence Rule.