| 51 | | When the layout template is executed, `DISK_VOLUME_PARAMS` already exists with some typical default entries. For this reason, the layout template doesn't create the variable from scratch with function `nlist()` but uses the function `filesystem_mod()` to update it. This is also for this reason that in the examples ( |
| 52 | | |
| 53 | | This should be done as demonstrated in the [source:templates/trunk/sites/example/site/filesystems/glite.tpl example], using function `filesystem_mod()`to update variable `DISK_VOLUME_PARAMS`. |
| | 51 | When the layout template is executed, `DISK_VOLUME_PARAMS` already exists with some typical default entries. For this reason, the layout template doesn't create the variable from scratch with function `nlist()` but uses the function `filesystem_mod()` to update it. This is also for this reason that in the examples ([source:templates/trunk/sites/example/site/filesystems/glite.tpl site/filesystems/glite.tpl], [source:templates/trunk/sites/example/site/filesystems/extended.tpl site/filesystems/extended.tpl], [source:templates/trunk/sites/example/site/filesystems/sw_raid.tpl site/filesystems/sw_raid.tpl]), file system entries like `root`, `usr` don't have a `mountpoint` attribute defined in the layout template. The defaults are defined in the file system [source:templates/trunk/standard/filesystem/config.tpl configuration template]. Look at `DISK_VOLUME_PARAMS` definition in it if you need to check what the default entries and attributes are. |
| | 52 | |
| | 53 | One important feature of the file system [source:templates/trunk/standard/filesystem/config.tpl configuration template] is that if an entry in `DISK_VOLUME_PARAMS` has a zero size, it will be removed from the list of file systems or block devices to create. The template will also ensure that if an entry has no explicit size defined but is using an underlying block device with a zero size it is also removed. For example, this may be the case for a software raid block device whose size is derived from the partitions it uses but is not explicitly defined. This is also the case for a file system relying on a raid block device. |
| | 54 | |
| | 55 | The defaults defined in the file system [source:templates/trunk/standard/filesystem/config.tpl configuration template] include the creation of a LVM volume group called `vg.01` using the unused part of the system disk. As a result, if you would like a file system configuration LVM-free, you need to update the entry for `vg.01` and define its size to 0. Look at [source:templates/trunk/sites/example/site/filesystems/sw_raid.tpl site/filesystems/sw_raid.tpl] (a pure software raid configuration) for an example. |
| | 56 | |
| | 57 | An other important feature demonstrated in some of the examples provided ([source:templates/trunk/sites/example/site/filesystems/extended.tpl site/filesystems/extended.tpl], [source:templates/trunk/sites/example/site/filesystems/sw_raid.tpl site/filesystems/sw_raid.tpl]) is how to control the creation order of partitions on a disk. This is done by defining a list (called `DISK_GLITE_PARTS` in the examples) that is used to determine the number appended to the base device when creating the partition (this can also be used for MD devices). Look at [source:templates/trunk/sites/example/site/filesystems/sw_raid.tpl site/filesystems/sw_raid.tpl] for an example. |
| | 58 | |
| | 59 | ''Note: you will not see this variable in [source:templates/trunk/sites/example/site/filesystems/glite.tpl site/filesystems/glite.tpl] because it relies on defaults provided by the file system [source:templates/trunk/standard/filesystem/config.tpl configuration template].'' |
| | 60 | |
| | 61 | Some useful hints helping to maitain `DISK_VOLUME_PARAMS`: |
| | 62 | * There is no need to explicitly declare charatacteristics of disk partitions or logical volumes. This is why you will not see entry for them in the examples. If an entry is using a disk partition (eg. a file system) and has a size attribute defined, a block device corresponding to the declared size will be created. If the partition number is greater or equal to 5, an extended partition will automatically be added as the fourth partition on the device. The same applies to LVM logical volumes but a file system using a logical volume is required to have an attribute `volgroup` defined. |
| | 63 | * A special value for the size attribute is -1. This means you want to use all the remaining unused space in the underlying block device (eg. partition or logical volume). The file system [source:templates/trunk/standard/filesystem/config.tpl configuration template] will ensure that this entry is created last in the underlying block device and that there is not 2 entries with a size of -1 in the same block device. |
