Disks and File systems

File system types

HelenOS currently supports the following file systems:

File system	/srv executable	Can be initrd FS	Has mk*fs utility	Status
TMPFS	tmpfs	yes	no	Stable
FAT	fat	yes	yes	Stable
locfs	locfs	no	no	Stable
Ext2fs/Ext3fs/Ext4fs	ext4fs	yes	no	Stable
exFAT	exfat	no	yes	Testing
CDFS	cdfs	no	no	Testing
MFS	mfs	no	yes	Stable
UDF	udf	no	no	Read-only testing

Directory structure

The file system of a running HelenOS system is roughly laid out as follows:

/app	end-user applications (see the Command Reference)
/cfg	system-wide configuration
/data	application data (e.g. the web root served by websrv)
/drv	device drivers
/inc	header files
/lib	libraries
/loc	location service nodes (rough analogy of /dev in UNIX)
/src	source files
/srv	server applications (services, e.g. console, networking - see the Command Reference)
/tmp	temporary files

This layout is not fixed in any way and may change in the future.

Block device drivers

Non-DDF:

file_bd	File-backed block device
part	Disk label/partition driver - provides block devices for individual partitions
rd	Initial ramdisk
sata_bd	AHCI SATA

DDF-based:

ata_bd	ATA/ATAPI
usbmast	USB mass storage
ddisk	msim disk driver

Working with disk labels and file systems

You can use the interactive fdisk utility to create and manage disk labels. BIOS/MBR and UEFI/GPT labels are supported. When you create a partition with fdisk, you are also prompted for file system type (The file system will be initialized as part of creating the partition).

If you'd like to create a file system on a raw disk, you need to do it by manually invoking a mk*fs utility.

Mounting file systems

In order to make use of a file system it needs to be mounted into the filesystem namespace using the mount command. Typing just mount<enter> prints out a list of mounted file systems. Te basic syntax to mount a file system is:

# mount <fstype> <service-name> <directory>

fstype is the type of the file system (e.g. ext4, mfs), service-name is the service name of the block device (typically of a partition) and directory is the directory path to mount on top of.

You can find the list of available partition block devices in your system by typing:

# loc show-cat partition

Unlabeled disks will be represented by one 'fake' partition spanning the entire disk.