[Bug 1513254] Re: iscsi_auto flag should use iscsistart -N in addition to -b

[Scott Moser]

This seems sane, my one concern is when the device attached with 'iscsistart -b' ends up being the root device.
In the other iscsi path (iscsi_target_name=.... iscsi_target_ip=... iscsi_target_port=... and 'ip=..') the 'ip' command writes the configured network information into /run/net-eth0.conf and then open-iscis's initramfs script writes 'eth0' to /run/initramfs/open-iscsi.interface .  That instructs open-iscsi's "net-interface-handler" to fake the configuring of 'eth0' without bringing it down.

So, in the iscsistart -N path we need some way to convince ifup that the
interface is up.  If the interface up code thinks it fails to bring the
network up (because its already up, or possibly even had different
config), then the network-online.target (static-networking-up in trusty)
might not fire, causing things that depend on it to not run.

Second thing I'm not sure of, is how interface names are kept consistent
between initramfs and post-initramfs.  Ie, if iscsistart -N brings up
the interface 'eth0', but /etc/network/interfaces and udev rules have
set that to be named 'eth1', I'm not what would happen.


Third thing, is if there was any networking needed beyond the things that iscsistart could configure (vlan or bonding or additional routes in the configured system for that interface) then I'm not sure if they'd get applied.

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https://bugs.launchpad.net/bugs/1513254

Title:
  iscsi_auto flag should use iscsistart -N in addition to -b

Status in open-iscsi package in Ubuntu:
  New

Bug description:
  Right now, the following logic is used if you pass iscsi_auto as a
  kernel option:

  modprobe iscsi_ibft
  iscsistart -b

  However, in a PXE boot environment, the interface initialized will be
  something like the "primary" interface of the system, probably not
  where your iscsi traffic is running.

  The '-N' flag of iscsistart should also be used to configure the
  networking before attempting to create a session to the target.

  so:

  iscsistart -Nb

  This change should go into the scripts/local-top/iscsi script.  I'll
  attach a patch.  Note that this code path is not traversed unless you
  are booting the kernel with iscsi_auto.  Also if you boot the kernel
  this way and you do not have IBFT in your ethernet adapter, you will
  already fall into an (initramfs) prompt as iscsistart -b will fail.

  The only consideration is if the IBFT does not have correct networking
  information in it, which should be a configuration error.

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