Mounting storage devices

Mounting drives using goetia services

goetia allows both mounting drives individually one per service and mounting by fstab. A service to run mount -a is provided for each supported Kernel and named mount-fstab The source directory is contained in the kernel specific packages: goetia-linux, goetia-freebsd, ... . Symlink the corresponding source directory if using the /etc/fstab file is desired. Then, add mount-fstab to the mount bundle. (See configuration directories) One still needs to properly write an /etc/fstab file based on the hardware configuration.

Doing mounting by creating one service for each storage medium to be mounted, as it is highly dependant on the number, setup and type of storage media used. This approach has distinct advantages:

• Parallelization:
  while some implementations of mount support the -f switch to mount all entrys of /etc/fstab in parallel, the order of mounting them is undefined. sdc1 to be mounted at /mnt/temp/subdir which only exists after sdb1 is mounted at /mnt/temp could randomly fail, if mount tries to process sdc1 before sdb1.
  When using one service for each mountpoint however, the service for mounting sdc1 can declare a dependency on sdb1 which allows for all other mounts to be done in parallel, whilst sdc1 is only mounted after sdb1.
• Dependency management:
  Say one runs a database which writes files to one specific drive only. The service can declare a dependency upon the mounting service only and does not have to wait until all of mount -a is finished.
• Potential for simplicity:
  Doing away with /etc/fstab makes it possible to use a simpler implementation of mount that does not need the code to parse /etc/fstab.

Therefore it is recommended to create one source directory per partition to be mounted. Examples on how to do this follow below.

Remount root

Once the Kernel starts init, the root filesystem is already mounted. This makes sense, since init itself and the software it uses usually reside there. The root filesystem is at this point mounted read-only and needs to be remounted read-write, to allow making changes. This is done by the remount-root oneshot. The source directory is yet again contained in the kernel specific packages: goetia-linux, goetia-freebsd, ... . Symlink it and add it to the mount bundle.

There are occasions where some initramfs prepares multiple drives. In some cases init as well as other software lives not on the root filesystem. In this case, create a specific remount oneshot for each partition. See the examples below.

The bundle mount

Many services that come with goetia depend on the bundle mount. Make sure this bundle contains the services that mount the partitions holding the data related to the service. This is usually the root partition, thus, add the service remount-root to the bundle mount.

Examples

General

To create a service for mounting a partition, create a source directory for a oneshot service at src/mount/mount-@PART@ in the system configuration directory with @PART@ being a descriptive name for the partitions purpose.

The dependencies.d directory needs to contain the mount-dev and mount-proc files, since those virtual file systems are used to mount the partitions. Dependending on the method used to identify the partition, mount-sys and udev might be additional dependencies.

The source directory should look as follows:

mount-@PART@
├── dependencies.d
│   ├── mount-dev
│   ├── mount-proc    # only on Linux if using the findfs functionallity
│   ├── mount-sys     # only on Linux if using the findfs functionallity
│   └── udev          # only on Linux if using the userspace device manager symlink
├── down              # see below
├── type              # oneshot
└── up                # see below
			

You should ony umount in the down script if you are sure that no programs(apart from those started by services depending on the mount service) use the partition. The down script for umounting is always the same:

#!/bin/execlineb -P

fdmove -c 2 1

umount /path/to/mountpoint
			

Now for the up script, which varys depending on the kernel used. Choose one of the solutions on identifying the correct partiton:

#!/bin/execlineb -P

fdmove -c 2 1

mount
   -o defaults
   /path/to/devicenode	# e.g. /dev/sda1
   /path/to/mount/point	# e.g. /mnt/media
				

#!/bin/execlineb -P

fdmove -c 2 1

backtick -E NODE { findfs UUID=@UUID@ }

mount
   -o defaults
   ${NODE}
   /path/to/mount/point	# e.g. /mnt/media
				

#!/bin/execlineb -P

fdmove -c 2 1

mount
   -o defaults
   /dev/disk/by-partuuid/@PARTUUID@   # or /dev/disk/by-uuid/@UUID@    # or /dev/disk/by-...
   /path/to/mount/point               # e.g. /mnt/media
				

#!/bin/execlineb -P

fdmove -c 2 1

mount
   -o remount,rw,defaults
   /path/to/mountpoint
				

#!/bin/execlineb -P

fdmove -c 2 1

mount
   -o defaults
   /path/to/devicenode	# e.g. /dev/sda1
   /path/to/mount/point	# e.g. /mnt/media
				

#!/bin/execlineb -P

fdmove -c 2 1

mount
   -o defaults
   /dev/diskid/@DISKID@   # or /dev/gptid/@GPTID@
   /path/to/mount/point   # e.g. /mnt/media
				

#!/bin/execlineb -P

fdmove -c 2 1

mount
   -uw
   /path/to/mountpoint