Format SSD MMC

About

Help tips for formatting:

• SSD (internal or external)
• MMC (μSD card - normal or recovery)
• USB drive

Can be done either from the camera or PC, the required programs are:

• fdisk - format into partitions
• mkfs.ext4 - create filesystem
• mkfs.vfat - create filesystem
• dd - clean filesystem from the partition for fast recording

SSD or USB

camera

• (not needed for USB) Check if SSD is connected to the camera:
  • The default connection is camera <=> internal SSD
  • For external drive set: camera <=> external SSD and power on the drive.
  • More info
• Find out the device name:

$ dmesg

• Check if it is already partitioned:

$ cat /proc/partitions

• manage partitions:

$ fdisk /dev/sda

• format a partition for file storage:

$ mkfs.ext4 /dev/sda1

• for fast recording
  • Do not make a file system on the partition

pc

The same as above except:

• For internal SSD the connection should be set to pc <=> internal SSD

MMC

camera

Make sure the camera is not boot from the MMC - in MMC boot by default the camera gets the boot files from /dev/mmcblk0p1 (FAT32) and mounts /dev/mmcblk0p2 (EXT4) as /.

• check boot mode:

$ mount | grep " / "

• check existing paritions:

$ cat /proc/partitions

• manage partitions:

$ fdisk /dev/mmcblk0

• format a partition for file storage:

mkfs.ext4 /dev/mmcblk0pX

pc

• Same as above except the MMC might be detected as /dev/sdX
• If MMC is for boot the partition table type must be msdos, not gpt

'Erase' a file system from a partition

Sometimes there is a need to this:

• if the drive was partitioned several times and the old file system journal starts from a location of a new partition - the file system will surely show up.
• by accident

Examples:

• Use dd:
  • 'Erase' a filesystem from /dev/sda1

$ dd if=/dev/zero of=/dev/sda bs=1MB count=1 seek=1

• 'Erase' a filesystem on /dev/sda2, if /dev/sda1 size is SIZE MB:

$ dd if=/dev/zero of=/dev/sda bs=1MB count=1 seek=SIZE

• To erase the drive's partition table (better use fdisk):

$ dd if=/dev/zero of=/dev/sda bs=512 count=2

Useful links

• git:elphel-tools-update - write_bootable_mmc.py
  • the script is used to create a bootable MMC from a PC (the camera doesn't have parted and kpartx installed)
  • it has examples of using dd, parted, mkfs, kpartx
• MMC boot
  • prepare a bootable μSD card and boot