HP Q153090901 - Manual (Page 20)

Interface Implementation 20
The values of the names can be obtained using the Device Identification Vital Product Information
Page (part of the INQUIRY command).
Implications for libraries
• Normally a standalone drive will operate using its own ‘hard’ names.
• The drive knows it is in a library or other ‘managed’ environment since one of the signal
lines on the ACI (Automation Control Interface) will be tied down.
In this case, the drive will not go on the FC loop until it is told to. The library can optionally
download a new, soft base name (Port A/Device Name) into the drive at this point. The drive
will then use this as the origin of its names. The library manufacturer would be responsible for
obtaining this IEEE Registered Name. It would be a property of the library, not the drive.
• If the library wants to ‘warm swap’ drives, it can. It just ‘turns off’ the drive with the soft
name using the ACI and then turns on the spare drive, downloading the same name to it.
• If a drive is removed from the library, it will not have the ACI signal tied low and so will
revert to its original hard name. It should forget the soft name in this case.
• If the library controller breaks, the drive will time out the ACI interface in ~10 seconds. The
drive still knows it is in a library since the ACI signal is still tied low, so in this case it will
use the soft name last downloaded. This will allow drive access without confusing the host.
Field replaceable units
An FRU code identifies which part of the hardware is considered to have failed. These codes turn
up in sense data byte 14 and as the sense code qualifier for sense codes 4400h (internal target
failure) and 40XX (diagnostic failure).