2008/640 iSCSI With DHCP

[James Carlson]

I'm sponsoring this fast-track request for Jack Meng.  The timer is
set to 10/24/2008.

Background

  By default, dhcpagent "canonizes" interfaces under its control on
  receipt of SIGTERM.  This means that it will reset the IP address
  back to 0.0.0.0 during shutdown.  This happens regardless of whether
  dhcpagent is configured to release or drop leases.

Problem

  When DHCP canonizes as a normal part of system shut-down, iSCSI may
  lose contact with the server.  If the system is diskless, and the
  root file system is mounted via iSCSI, this causes at least a
  lock-up and may cause data loss.

Solution

  Release binding for this change is Patch/Micro.

  A new Consolidation Private ioctl (ISCSI_IS_ACTIVE) will be added to
  "/devices/iscsi:devctl".  dhcpagent will invoke this ioctl to
  determine whether it can canonize interfaces on exit.

Related Projects and Future Work

  When the root file system is mounted via NFS, a completely different
  mechanism is used.  In this case, /sbin/netstrategy indicates a
  "dhcp" boot, and we start dhcpagent with the somewhat obscure "-a"
  (adopt) flag.  In addition to pulling DHCPACK information from OBP,
  this causes dhcpagent to avoid canonizing on shutdown (per CR
  4291141).

  This entire area is one that requires future study, in particular
  for the relationship between booting, interface configuration,
  system shutdown sequencing, and SMF.  However, that is not this
  project.

References

  6751246 dhcp release the lease before sync is committed on iSCSI disk
  PSARC 2008/427 iSCSI Boot
  4291141 Reboot after install w/DHCP hangs due to dhcpagent
	  canonizing interface
  6701045 iSCSI boot on x86

-- 
James Carlson, Solaris Networking              <james.d.carlson at sun.com>
Sun Microsystems / 35 Network Drive        71.232W   Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757   42.496N   Fax +1 781 442 1677