NAME

newfs_hammer2 — construct a new HAMMER2 file system

SYNOPSIS

DESCRIPTION

The newfs_hammer2 utility prepares a HAMMER2 volume on the specified block device. HAMMER2 volumes can contain any number of named PFSs (Pseudo FileSystems).

The newfs_hammer2 program always creates a PFS called "LOCAL" which may be used for device-specific configuration. This PFS should never be used for generic data.

If no -L option is specified, newfs_hammer2 will create "DATA".

You can override the default PFS name by specifying one or more -L options.

You can specify -L none if you do not want newfs_hammer2 to create any PFSs other than "LOCAL".

HAMMER2 file systems are sector-size agnostic, however the DragonFly implementation requires the sector size to be no larger than 16K. HAMMER2 file systems start at a relative offset of 0 and leave no room for in-band disklabels (old, traditional BSD labels). They may only be created using out-of-band disk labels, which is the default on DragonFly via (disklabel(5) or gpt(8) labels), or with old style disklabels as long as the partition does not overlap the label area (have a starting sector greater than 16).

HAMMER2 file systems are designed for large storage systems, up to 1 Exabyte, and may not operate efficiently on small storage systems. The minimum recommended file system size is 50GB. In addition, HAMMER2 file systems operating normally, with automatic snapshots, do not immediately reclaim space when files are deleted. A regular system maintenance job runs once a day by periodic(8) to handle reclamation.

HAMMER2 works best when the machine's normal workload would not otherwise fill the file system up in the course of 60 days of operation.

The options are as follows:

-b bootsize

Specify a fixed area in which a boot related kernel and data can be stored. The bootsize is specified in bytes. By default a boot area of approximately 64MB will be created. This area is not currently used for booting and may be repurposed in the future.

-r auxsize

Specify a fixed area in which an aux related kernel and data can be stored. The auxsize is specified in bytes. By default an aux area of approximately 256MB will be created. This area is not currently used and may be repurposed in the future.

-V version

Specify the HAMMER2 file system version to format. By default newfs_hammer2 formats the file system using the highest production version number supported by the HAMMER2 VFS by checking the vfs.hammer2.supported_version sysctl. If you need to maintain compatibility with an older version of HAMMER2 you may specify the version with this option.

-L label

By default newfs_hammer2 always creates a local master PFSs on the new volume called "LOCAL" and "DATA".

If you specify one or more label options to create your own named local PFSs, newfs_hammer2 will not create any conditional PFSs. However, "LOCAL" is still always created and should not be specified with this option. If you don't want any PFSs to be created (other than "LOCAL"), use -L none.

-s size

The size of the file system in bytes. This value defaults to the total size of the raw partitions specified in special (in other words, newfs_hammer2 will use the entire partition for the file system). The size must be 1GiB or larger.

The bootsize, auxsize and size must be given with a suffix of K, M, G or T meaning kilobyte, megabyte, gigabyte and terabyte. Lower case can also be used for suffix. The bootsize and auxsize create reserved blocks of space on the target volume but are not currently used by the filesystem for anything.

EXIT STATUS

The newfs_hammer2 utility exits 0 on success, and >0 if an error occurs.

SEE ALSO

hammer2(8), mount_hammer2(8)

HISTORY

The newfs_hammer2 utility first appeared in DragonFly 3.1 but was not enabled unconditionally until DragonFly 4.9.

AUTHORS

Matthew Dillon <dillon@backplane.com>

The newfs_hammer2 utility was ported to FreeBSD, NetBSD and OpenBSD by
Tomohiro Kusumi <tkusumi@netbsd.org>.