[openstack-dev] [ironic] Kernel parameters needed to boot from iscsi

Derek Higgins derekh at redhat.com
Wed Oct 25 13:55:54 UTC 2017


On 25 October 2017 at 13:03, Dmitry Tantsur <dtantsur at redhat.com> wrote:
> (ooops, I somehow missed this email. sorry!)
>
> Hi Yolanda,
>
> On 10/16/2017 11:06 AM, Yolanda Robla Mota wrote:
>>
>> Hi
>> Recently i've been helping some customers in the boot from ISCSI feature.
>> So far everything was working, but we had a problem when booting the
>> deployment image.
>> It needed specifically a flag rd.iscsi.ibft=1 rd.iscsi.firmware=1 in the
>> grub commands. But as the generated deployment image doesn't contain these
>> flags, ISCSI was not booting properly. For other hardware setups, different
>> flags may be needed.
>
>
> Note that we only support BFV in the form of booting from a cinder volume
> officially. We haven't looked into iBFV in depth.
>
>> The solution was to manually execute a virt-customize on the deployment
>> image to hardcode these parameters.
>> I wonder if we can add some feature in Ironic to support it. We have
>> discussed about kernel parameters several times. But at this time, it
>> affects ISCSI booting. Not having a way in Ironic to customize these
>> parameters forces to manual workarounds.
>
>
> This has been discussed several times, and every time the idea of making it
> a generic feature was rejected. There is an option to configure kernel
> parameters for PXE boot. However, apparently, you cannot add
> rd.iscsi.firmware=1 if you don't use iSCSI, it will fail to boot (Derek told
> me that, I did not check).
When I tried it I got this
[  370.704896] dracut-initqueue[387]: Warning: iscistart: Could not
get list of targets from firmware.

perhaps we could alter iscistart to not complain if there are no
targets attached and just continue, then simply always have
rd.iscsi.firmware=1 in the kernel param regardless of storage type

> If your deployment only uses iSCSI - you can
> modify [pxe]pxe_append_params in your ironic.conf to include it.

I'm not sure this would help, in the boot from cinder volume case the
iPXE script simply attaches the target and then hands control over to
boot what ever is on the target. The kernel parameters use are already
baked into the grub config. iPXE doesn't alter them and IPA isn't
involved at all.

If anybody is looking to try any of this out in tripleo, here are some
instructions to boot from cinder volume with ironic on a tripleo
overcloud
https://etherpad.openstack.org/p/tripleo-bfv

>
>
>> So can we reconsider the proposal to add kernel parameters there? It could
>> be a settable argument (driver_info/kernel_args), and then the IPA could set
>> the parameters properly on the image. Or any other option is welcome.
>> What are your thoughts there?
>
>
> Well, we could probably do that *for IPA only*. Something like
> driver_info/deploy_image_append_params. This is less controversial than
> doing that for user instances, as we fully control the IPA boot. If you want
> to work on it, let's start with a detailed RFE please.
>
>>
>> Thanks
>>
>> --
>>
>> Yolanda Robla Mota
>>
>> Principal Software Engineer, RHCE
>>
>> Red Hat
>>
>> <https://www.redhat.com>
>>
>> C/Avellana 213
>>
>> Urb Portugal
>>
>> yroblamo at redhat.com <mailto:yroblamo at redhat.com> M: +34605641639
>> <http://redhatemailsignature-marketing.itos.redhat.com/>
>>
>> <https://red.ht/sig>
>>
>>
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