Backup master node - Inadequate free space to compress file

[Egor Kotko]

{"build_id": "2014-07-14_02-01-14", "ostf_sha": "9863db951a6e159f4fa6e6861c8331e1af069cf8", "build_number": "317", "auth_required": false, "api": "1.0", "nailgun_sha": "638f4e09c5696d549482fabd0116f6008973291a", "production": "docker", "fuelmain_sha": "f32b958788e9d7acd904b31962b6bb71f9b66766", "astute_sha": "d68cc542290b3176b7a556eb9accba5a38a88519", "feature_groups": ["mirantis"], "release": "5.1", "fuellib_sha": "1b17a7999969d87babbc7a07ba1c5c805d1588d8"}

Steps to reproduce:
1. Download latest iso
2. Setup master node with hdd size 30720 mb
3. Execute on master command:
#dockerctl backup

Expected result:
Created archive in default directory /var/backup/fuel/

Actual result:
Backup finished with error:
"Possibly inadequate free space to compress file, use -f to override.
Fatal error - exiting"

[Matthew Mosesohn (raytrac3r)]

will be covered in https://review.openstack.org/#/c/106076/