[Bug 1075313] Re: no reliable way to boot from iscsi root

[Scott Moser]

Thanks to Dave's comment above, I successfully  booted a precise ephemeral image with the following patch applied to maas:
--- /usr/share/pyshared/provisioningserver/kernel_opts.py.dist  2013-01-31 15:43:30.419250392 -0500
+++ /usr/share/pyshared/provisioningserver/kernel_opts.py       2013-01-31 15:49:09.991260224 -0500
@@ -136,7 +136,9 @@
             # in the initramfs.
             "ip=::::%s:BOOTIF" % params.hostname,
             # cloud-images have this filesystem label.
-            "ro root=LABEL=cloudimg-rootfs",
+            "ro root=/dev/disk/by-path/ip-%s:%s-iscsi-%s:%s-lun-1" % (
+                 params.fs_host, "3260", ISCSI_TARGET_NAME_PREFIX,
+                 get_ephemeral_name(params.release, params.arch)),
             # Read by overlayroot package.
             "overlayroot=tmpfs",
             # Read by cloud-init.

Basically, that ends up with a cmdline like:
nomodeset iscsi_target_name=iqn.2004-05.com.ubuntu:maas:maas-precise-daily-amd64-ephemeral-20130107 iscsi_target_ip=10.98.191.16 iscsi_target_port=3260 iscsi_initiator=maas-enlist ip=::::maas-enlist:BOOTIF ro root=/dev/disk/by-path/ip-10.98.191.16:3260-iscsi-iqn.2004-05.com.ubuntu:maas:maas-precise-daily-amd64-ephemeral-20130107-lun-1 overlayroot=tmpfs cloud-config-url=http://10.98.191.16/MAAS/metadata/latest/enlist-preseed/?op=get_enlist_preseed log_host=10.98.191.16 log_port=514 -- console=ttyS0,115200 initrd=amd64/generic/precise/commissioning/initrd.gz BOOT_IMAGE=amd64/generic/precise/commissioning/linux BOOTIF=01-52-54-00-06-e4-d5

This may well be sufficent for our needs.


** Also affects: maas
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1075313

Title:
  no reliable way to boot from iscsi root

Status in MAAS:
  New
Status in “open-iscsi” package in Ubuntu:
  Triaged

Bug description:
  In order to boot from iscsi root via kernel parameters, the user would provide kernel parameters something like:
     iscsi_target_name=some-iscsi-target-name iscsi_target_port=3260 iscsi_target_ip=some.host root=LABEL=SOME_LABEL

  or potentially the same above but with root=UUID=SOME_UUID.

  The issue here is that this both LABEL and UUID could collide with a
  local filesystem.   Perhaps a previous install left a filesystem
  labeled "rootfs" that happened to match the filesystem of the
  iscsi_target_name and now using "root=LABEL=rootfs".  The same is
  possible with UUID.

  There needs to be some way to specify explicitly:
     root=iscsi_target_name=some-iscsi-target-name that would make the iscsi initialization code guaranteed to boot with the appropriate root device independent of whatever local filesystems might have.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.10
  Package: open-iscsi 2.0.873-3ubuntu5
  ProcVersionSignature: Ubuntu 3.5.0-17.28-generic 3.5.5
  Uname: Linux 3.5.0-17-generic x86_64
  ApportVersion: 2.6.1-0ubuntu6
  Architecture: amd64
  Date: Mon Nov  5 15:25:48 2012
  MarkForUpload: True
  ProcEnviron:
   LANGUAGE=en_US:
   TERM=screen
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: open-iscsi
  UpgradeStatus: No upgrade log present (probably fresh install)

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