====== mkfs.xfs ======

  * [[XFS]]
  * [[mount]]
  * [[xfs_info]]

  * [[http://oss.sgi.com/projects/xfs/training/xfs_slides_04_mkfs.pdf|XFS Overview & Internals: mkfs]]
  * [[http://oss.sgi.com/projects/xfs/training/xfs_slides_05_mount.pdf|XFS Overview & Internals: mount]]
  * [[http://oss.sgi.com/projects/xfs/training/xfs_lab_02_mkfs.pdf|XFS Practical Exercises: mkfs & mount]]

Creating an XFS filesystem can use a partition or the logical device directly.

<code>
mkfs.xfs /dev/sda1
mkfs.xfs /dev/sdb
</code>

Do a dry-run and see what filesystem attributes it would set:

<code>
mkfs.xfs -N /dev/sda1
</code>

If the device already has another filesystem, mkfs will stop.  You can safely force it to run:

<code>
mkfs.xfs -Nf /dev/sda1
</code>

==== Performance ====

For the sake of clarity (and not making mistakes) when using additional arguments, use ''mkfs.xfs -d name=/dev/sda'' syntax when creating filesystems instead of ''mkfs.xfs /dev/sda''

=== External Log ===

The journal log can be put on a separate device to improve performance.

<code>
mkfs.xfs -d name=/dev/sda -l logdev=/dev/sdb
mount -o logdev=/dev/sdb /dev/sda /mnt/xfs
</code>

=== External Metadata ===

In addition to having the journal log on a separate device, the metadata and file data can be split up as well.

Create the new XFS filesystem and separate log journal at the same time:

<code>
mkfs.xfs -d name=/dev/sda -l logdev=/dev/sdb -r rtdev=/dev/sdc
mount -o logdev=/dev/sdb,rtdev=/dev/sdc /dev/sda /mnt/xfs
</code>

=== Internal Log Block Sizes ===

In both cases, the logdev option will want a block size.  See ''man mkfs.xfs'' for syntax, suggestions.

Alternatively, see what ''mkfs.xfs'' would use by default, and use that:

<code>
mkfs.xfs -Nf -d name=/dev/sda
</code>

<code>
meta-data=/dev/sda               isize=256    agcount=4, agsize=524288 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=0        finobt=0
data     =                       bsize=4096   blocks=2097152, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=0
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
</code>

<code>
mkfs.xfs -d name=/dev/sda -l logdev=/dev/sdb,size=2560b
</code>