HP-UX iSCSI Software Initiator Support Guide, HP-UX 11i v1 and 11i v2, July 2005

Chapter 7

The iSCSI Software Interface Driver

iSCSI Software Interface Driver Technical Overview

System Startup

In the standard HP-UX system startup sequence, access to mass storage is established before networking is

initialized. This order of events is in conflict with the iSCSI SWD, because iSCSI target devices cannot be

accessed prior to networking initialization.

When the iSCSI SWD attempts to:

— discover iSCSI targets

— activate volume groups with physical volumes on iSCSI targets

— access file systems on iSCSI targets

before network initialization is completed, the ENETUNREACH errno is returned to the caller. The Logical

Volume Manager ( LVM ) will not generate an error message when it sees this errno.

Administrative commands that access iSCSI targets will also return the ENETUNREACH errno until

networking is initialized. Upon seeing the errno, the administrative commands will not generate an error

message.

Once the first attempt at network initialization is complete, the ENETUNREACH errno will no longer be

returned. Any errno that is returned will be the same as if iSCSI were not installed in the system.

The iSCSI Software Intitiator startup script has been modified to perform iSCSI target access operations a

second time after networking has been initialized.

The resolution of the ordering problems described above has placed limitations on the iSCSI SWD. Because

network initialization is performed using the /var directory, the /var directory cannot be on an iSCSI target.

Also, the boot, root, primary swap, and dump file systems are not supported on iSCSI volumes.