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DESCRIPTION

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 use the partition id to create a default label for you.

partition 'a'

"BOOT" is created.

partition 'd'

"ROOT" is created.

otherwise

"DATA" is created.

You can override the default PFS name by specifying one or more -L options. By default these PFSs all represent unclustered mount points.

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

Generally speaking this command is not used to create clusters. It is used to format volumes which are then made available for additional clustering commands. Once formatted the device@LOCAL volume can be mounted in order to make it and all other PFSs created on the volume available to the cluster.

You can use hammer2(8) directives to construct your cluster, including the creation of additional PFSs within various volumes. If you are managing several machines, or a large number of machines, -L none is typically specified to reduce clutter.

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.

-f

Force operation. This is needed for the creation of a HAMMER2 file system less than 10GB size or with less than 500MB UNDO/REDO FIFO. This should not be used under normal circumstances.

-r redosize

Specify the size of the fixed REDO FIFO. The redosize is specified in bytes. By default 0.1% of the root volume's size is used, with a reasonable minimum and a reasonable cap. The UNDO/REDO FIFO is used to sequence meta-data out to the media for instant crash recovery.

-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 will conditionally also create "BOOT", "ROOT", or "DATA" depending on the partition ('b' creates "BOOT", 'd' creates "ROOT", and any other partition creates "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.

Typically simple HAMMER2 filesystems just use the defaults and -L none is used for more complex filesystem, followed by mounting device@LOCAL and using hammer2 directives to create the desired cluster.

The bootsize and redosize 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. These options create reserved blocks of space on the target volume but are not currently used by the filesystem for anything.

newfs_hammer2 -L SATURN-HOME /dev/ad0s1d