HP-UX iSCSI Software Initiator Support Guide (Edition 7)

7.7 iSCSI Software Interface Driver Statistics
Statistics are maintained in the iSCSI Software Interface Driver (SWD). For a detailed listing and
explanation of the iSCSI Software Interface Driver statistics see Appendix D (page 53).
7.8 iSCSI Software Interface Driver Diagnostic Messages
By default, the iSCSI Software Interface Driver logs all diagnostic messages to the Support Tools
Manager (STM) log files. At the time of this publication, there is no support to display messages
logged by the iSCSI driver in the HP-UX 11i v3 version of STM. When this support is released,
STM can be used to view these diagnostic messages.
EMS can be configured to automatically notify the system administrator when diagnostic messages
are logged by the iSCSI Software Interface Driver.
In addition to logging all diagnostic messages to the STM log files, the iSCSI Software Interface
Driver logs some of the diagnostic messages to the /var/adm/syslog/syslog.log file.
For a detailed listing and explanation of messages that the iSCSI Software Interface Driver can
generate, see Appendix E (page 59).
7.9 iSCSI Software Interface Driver Daemons
7.9.1 iSCSI Software Interface Driver Daemon (iswd)
The iSCSI SWD daemon, iswd, is a user level process that communicates with the iSCSI SWD
component and the network sockets interface. The iSCSI SWD daemon will receive requests to
open or close a connection, then it will use the existing application network socket interface to
perform the connection open/close operation. Once a connection has been established, the iSCSI
SWD daemon will use a system call to inform the iSCSI SWD that the connection is available (on
open), the connection attempt failed (on open), or the connection was successfully closed.
A client process forked from the iswd daemon would establish/manage all the connections. If the
number of connections to be managed exceeds the value in the “maxfiles” kernel tunable, another
client process is spawned to establish/manage new connections.
When the iSCSI SWD daemon initializes, it will bind a module into the connection path in the
kernel. Requests to and from the TCP stack will pass through the kernel component. The kernel
component will be provided with an entry point into the iSCSI SWD, and, on successful open, the
iSCSI SWD will be provided with an entry point into the kernel module. Once the open is complete,
data transfers can be made between the iSCSI SWD and kernel module without iSCSI SWD
daemon involvement, thus eliminating copies between user and kernel space.
38 The iSCSI Software Interface Driver