docs: image format details -> advanced section

docs/advanced.rst

 Advanced Topics
 ===============
 
+.. _image-format-advanced:
+
+Image Format
+^^^^^^^^^^^^
+
+snf-image supports 3 types of image formats:
+
+ * **extdump**: a raw dump of an ext{2,3,4} file system
+ * **ntfsdump**: a raw dump of an NTFS file system
+ * **diskdump** (recommended): a raw dump of a disk
+
+extdump and ntfsdump image formats
+++++++++++++++++++++++++++++++++++
+
+Those two formats are dumps (raw copies using dd) of partitions hosting Linux
+systems on ext{2,3,4} and Windows systems on ntfs file systems respectively.
+Partitions hosting a Windows or Linux system that are suitable for dumping
+should have the following properties:
+
+ * Be the first partition in the file system
+ * The OS they host should not depend on any other partitions
+ * Start at sector 2048
+ * Have a boot loader installed in the boot sector of the partition (not MBR)
+ * Have the root device in */etc/fstab* specified in a persistent way, using
+   UUID or LABEL (for extdump only)
+
+Known Issues
+------------
+
+ * For Linux systems, having grub installed in the partition is fragile and
+   things can go wrong when resizing the partitions, especially when shrinking.
+ * More complicated partition schemes are not supported.
+
+diskdump image format (recommended)
++++++++++++++++++++++++++++++++++++
+
+Diskdump is a newer format that overcomes most of the aforementioned issues.
+This format is a dump (raw copy using dd) of a whole disk.
+
+This design decision has the following benefits:
+
+ * Swap partitions are supported
+ * The system may use multiple partitions:
+    * dedicated partitions for /boot, /home etc in Linux
+    * system and boot partition in Windows
+ * There are no restrictions on starting sectors of partitions
+
+Although diskdump is a lot more flexible than the older formats, there are
+still some rules to follow:
+
+ * All devices in fstab should be specified by persistent names (UUID or LABEL)
+ * LVMs are not supported
+ * For Linux disks only ext{2,3,4} file systems are supported
+ * For FreeBSD disks only UFS file systems are supported
+ * For FreeBSD only GUID Partition Tables (GPT) are supported
+
 Progress Monitoring Interface
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

docs/usage.rst

@@ -24,56 +24,17 @@ following OS Parameters:
 Image Format
 ^^^^^^^^^^^^
 
-Right now 3 different types of image formats are supported:
+snf-image supports 3 different types of image formats:
 
+ * **diskdump** (recommended): a raw dump of a disk
  * **extdump**: a raw dump of an ext{2,3,4} file system
  * **ntfsdump**: a raw dump of an NTFS file system
- * **diskdump**: a raw dump of a disk
 
-extdump and ntfsdump image formats
-++++++++++++++++++++++++++++++++++
-
-Those two formats are dumps (raw copies using dd) of partitions hosting Linux
-systems on ext{2,3,4} and Windows systems on ntfs file systems respectively.
-Partitions hosting a Windows or Linux system that are suitable for dumping
-should have the following properties:
-
- * Be the first partition in the file system
- * The OS they host should not depend on any other partitions
- * Start at sector 2048
- * Have a boot loader installed in the boot sector of the partition (not MBR)
- * Have the root device in */etc/fstab* specified in a persistent way, using
-   UUID or LABEL (for extdump only)
-
-Known Issues
-------------
-
- * For Linux systems, having grub installed in the partition is fragile and
-   things can go wrong when resizing the partitions, especially when shrinking.
- * More complicated partition schemes are not supported.
-
-diskdump image format
-+++++++++++++++++++++
-
-Diskdump is a newer format that overcomes most of the aforementioned issues.
-This format is a dump (raw copy using dd) of a whole disk.
-
-This design decision has the following benefits:
-
- * Swap partitions are supported
- * The system may use multiple partitions:
-    * dedicated partitions for /boot, /home etc in Linux
-    * system and boot partition in Windows
- * There are no restrictions on starting sectors of partitions
-
-Although diskdump is a lot more flexible than the older formats, there are
-still some rules to follow:
-
- * All devices in fstab should be specified by persistent names (UUID or LABEL)
- * LVMs are not supported
- * For Linux disks only ext{2,3,4} file systems are supported
- * For FreeBSD disks only UFS file systems are supported
- * For FreeBSD only GUID Partition Tables (GPT) are supported
+These are also the only valid values for the **img_format** OS parameter.
+The **diskdump** type is the newest and recommended type. Thus, all sample
+images we provide are of this type. For more details about the internals of
+image formats please see the :ref:`corresponding advanced section
+<image-format-advanced>`.
 
 .. _image-id: