From 25dbdb7dc707e5b65d49d05baefaa267c8659669 Mon Sep 17 00:00:00 2001 From: Arne Wiebalck Date: Thu, 2 Jul 2020 14:17:42 +0200 Subject: [PATCH] [doc] Describe how to extract an fs UUID from an image For software RAID, the image needs to have the root filesystem UUID as metadata. This patch describe how to extract this UUID from an existing image. Change-Id: Ifdb63a80d4138a41fd0bac9880d14c90a4378fe5 --- doc/source/admin/raid.rst | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/doc/source/admin/raid.rst b/doc/source/admin/raid.rst index 5d32f170f8..38753d6989 100644 --- a/doc/source/admin/raid.rst +++ b/doc/source/admin/raid.rst @@ -410,7 +410,17 @@ have its root file system on the first partition. Starting with Ussuri, the image can also have additional metadata to point Ironic to the partition with the root file system: for this, the image needs to set the ``rootfs_uuid`` property with the file system UUID of the root file -system. The pre-Ussuri approach, i.e. to have the root file system on +system. One way to extract this UUID from an existing image is to +download the image, mount it as a loopback device, and use ``blkid``: + +.. code-block:: bash + + $ sudo losetup -f + $ sudo losetup /dev/loop0 /tmp/myimage.raw + $ sudo kpartx -a /dev/loop0 + $ blkid + +The pre-Ussuri approach, i.e. to have the root file system on the first partition, is kept as a fallback and hence allows software RAID deployments where Ironic does not have access to any image metadata (e.g. Ironic stand-alone).