[mdlug] Create an XFS file system in freespace

[Robert Meier]

R,

> I want to create an XFS in the freespace available on my hard drive
> for storing MPEG video files created by MythTV.
> Apparently MythTV does not work well with ReiserFS (Ver3) that I have.
> If I understand correctly to do this, I have to 

> 1) Create a partition using 'cfdisk'.
> But cfdisk presents a lot of file system types (default is Linux? type 82)
> but not XFS. Which one do I choose?

linux nominally uses
0x82 - swap
0x83 - data (xfs, and most other filesystems, are layered on top)
0x85 - extended

Consequently for storing video files, you want to use partition type 83.

See http://www.win.tue.nl/~aeb/partitions/partition_types-1.html
for further details.

> 2) Create a file system using 'mkfs -t xfs /dev/sda10'[.]

There is some ambiguity here.  I believe /dev/sda10 refers to the 6th
extended partition, not to a primary partition.  See hd(4) and sd(4)
for details.

An extended partition is a section of a primary partition delineated
by an "extended boot record" stored in the primary partition.

It is analagous to a big file stored in the primary partition and
mounted loopback.
If the primary partition (or table entry) is damaged,
you probably lose the extended partition, 

It differs from a loopack file,
in that the parent "filesystem" data is read only once,
at mount-time, rather than potentially at each disk access.
This shaves a few microseconds off each disk access,
at the cost of potentially more disk fragmentation.

Assuming your video files have more value than average files on your
hard disk, I suggest creating a primary partition, or directory within
a primary partition.  To achieve this, you may need to copy current
contents to a temporary location, reformat the primary partition
as xfs, then copy the current contents back into a directory that
you can symlink if desired.

> Are there any options that I should use?

In addition to -t xfs, I recommend -c to check for bad sectors before
writing the filesystem.

See mkfs.xfs(8) for further details.

-- 
Bob

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