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Vfat config drive format support

asked 2014-10-23 03:21:17 +0300

alrick gravatar image

updated 2014-10-23 03:22:38 +0300

In Piston OpenStack we use config_drive_format=vfat to prevent data loss during instance block migrations (because libvirt does not block migrate virtual cdrom devices), but current cloud-init release supports only iso9660 config drive format.

Do you have plans to add vfat support as well in the future?

Thanks in advance.

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answered 2014-10-23 11:42:02 +0300

alexpilotti gravatar image

The issue is that the VFAT config drive is a so called RAW partition (e.g. on Linux you'd mount it directly as /dev/sdb, not /dev/sdb1) and this is not supported by Windows, where a partitioning scheme is required (e.g. MBR) in order to mount a partition.

What we can do is to extract the raw block data from the disk, put them in a vfd file and mount that as a loopback device (Windows 2008 R2 / Windows 7 and above). Being this a non trivial implementation we always left it as a low priority feature request due to the availability of the ISO option.

Note: the libvirt (KVM) live migration issue with config drives has been fixed in Juno:

This bug fix is worth a backporting to Icehouse as well IMO.

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Thank you very much for the answer!

alrick gravatar imagealrick ( 2014-10-23 23:29:31 +0300 )edit

I have some good news. Incidentally we're working on another project which involves VFAT images and it looks like I have a solution for this. Would you be interested in beta testing it?

alexpilotti gravatar imagealexpilotti ( 2014-10-24 01:21:42 +0300 )edit

Thanks for the update! Sure we would like to take a look at the solution.

alrick gravatar imagealrick ( 2014-10-24 01:33:25 +0300 )edit

FYI, we have VFAT ConfigDrive support since march.

cpopa gravatar imagecpopa ( 2015-04-06 20:07:07 +0300 )edit

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Asked: 2014-10-23 03:21:17 +0300

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Last updated: Oct 23 '14