What I don't understand is the way the archive is "saved":

Using bz2 decompression
downloading file:///tftpboot/eltf/standard/Enea_Linux_7.0_raspberrypi3-64_enea-image-standard_2017-12-14_16-47-18/images/raspberrypi3-64/enea-image-standard-raspberrypi3-64.tar.bz2
saving as /var/lib/lava/dispatcher/tmp/525/tftp-deploy-jBJXcy/nfsrootfs/enea-image-standard-raspberrypi3-64.tar

Just to answser this question: the archive is decompressed on the fly (while downloading) so the resulting file is a ".tar".

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Rémi Duraffort
LAVA Team