Image Format
Version 7 (Nikos Skalkotos, 11/23/2011 05:00 pm)
| 1 | 1 | Nikos Skalkotos | h1. Image Format |
|---|---|---|---|
| 2 | 1 | Nikos Skalkotos | |
| 3 | 4 | Nikos Skalkotos | Right now we support 4 different types of images: |
| 4 | 4 | Nikos Skalkotos | * extdump |
| 5 | 4 | Nikos Skalkotos | * ntfsdump |
| 6 | 4 | Nikos Skalkotos | * diskdump |
| 7 | 4 | Nikos Skalkotos | * custom |
| 8 | 1 | Nikos Skalkotos | |
| 9 | 4 | Nikos Skalkotos | h2. extdump & ntfsdump |
| 10 | 4 | Nikos Skalkotos | |
| 11 | 4 | Nikos Skalkotos | Those two formats are raw copies (using dd) of partitions hosting Linux systems on ext{2,3,4} and Windows systems on ntfs filesystems respectively. |
| 12 | 4 | Nikos Skalkotos | |
| 13 | 5 | Nikos Skalkotos | Partitions hosting a Windows or Linux system that are suitable for dumping should have the following properties: |
| 14 | 1 | Nikos Skalkotos | * Be the first partition in the filesystem |
| 15 | 5 | Nikos Skalkotos | * The OS they host should not depend on any other partitions |
| 16 | 1 | Nikos Skalkotos | * Start at sector 2048 |
| 17 | 1 | Nikos Skalkotos | * Have a bootloader installed in the partition |
| 18 | 5 | Nikos Skalkotos | * Have the root device in /etc/fstab specified in a persistent way, using UUID or LABEL (for extdump only) |
| 19 | 3 | Nikos Skalkotos | |
| 20 | 4 | Nikos Skalkotos | h3. Known Issues |
| 21 | 1 | Nikos Skalkotos | |
| 22 | 1 | Nikos Skalkotos | * For linux systems, having grub installed in the partition is fragile and things can go wrong when resizing the partitions, especially when shrinking. |
| 23 | 3 | Nikos Skalkotos | * Swap space is not supported. |
| 24 | 3 | Nikos Skalkotos | * More complicated partition schemes are not supported. |
| 25 | 3 | Nikos Skalkotos | |
| 26 | 1 | Nikos Skalkotos | h2. diskdump |
| 27 | 1 | Nikos Skalkotos | |
| 28 | 7 | Nikos Skalkotos | Diskdump is a newer format that overcomes most of the aforementioned issues. This format is a raw copy (dd) of a whole disk. |
| 29 | 1 | Nikos Skalkotos | |
| 30 | 7 | Nikos Skalkotos | This design decision has the following benefits: |
| 31 | 5 | Nikos Skalkotos | * Swap partitions are supported |
| 32 | 5 | Nikos Skalkotos | * The system may use multiple partitions: |
| 33 | 5 | Nikos Skalkotos | ** dedicated partitions for /boot, /home etc in linux |
| 34 | 5 | Nikos Skalkotos | ** system and boot partition in Windows |
| 35 | 7 | Nikos Skalkotos | * There are no restrictions on starting sectors of partitions |
| 36 | 5 | Nikos Skalkotos | |
| 37 | 5 | Nikos Skalkotos | Although diskdump is a lot more flexible that the older formats, there are still some rules to follow: |
| 38 | 5 | Nikos Skalkotos | * All devices in fstab should be specified by persistent names (UUID or LABEL) |
| 39 | 6 | Nikos Skalkotos | * LVMs and extended partitions should be avoided. |
| 40 | 6 | Nikos Skalkotos | ** The support for extended partitions is partial. snf-image does not support resizing logical partitions. |
| 41 | 6 | Nikos Skalkotos | ** Logical volumes are not supported at all |
| 42 | 6 | Nikos Skalkotos | * In Linux disks only ext{2,3,4} filesystems are supported |
| 43 | 6 | Nikos Skalkotos | |
| 44 | 6 | Nikos Skalkotos | h3. Image Properties |
| 45 | 6 | Nikos Skalkotos | |
| 46 | 6 | Nikos Skalkotos | In order for snf-image to be able to properly configure a diskdump image it needs to be aware some of image properties: |
| 47 | 6 | Nikos Skalkotos | |
| 48 | 6 | Nikos Skalkotos | * *OSFAMILY={linux|windows}* |
| 49 | 6 | Nikos Skalkotos | This specifies whether the image is a Linux or a Windows Image |
| 50 | 6 | Nikos Skalkotos | |
| 51 | 1 | Nikos Skalkotos | * *ROOT_PARTITION=[1234]* |
| 52 | 6 | Nikos Skalkotos | This specifies the partition number of the root partition. As mentioned earlier, for now we only support primary partitions |
| 53 | 6 | Nikos Skalkotos | |
| 54 | 7 | Nikos Skalkotos | * *USERS="username1 username2...."* |
| 55 | 7 | Nikos Skalkotos | This is a list of users, snf-image should try to reset the password for. |