[ale] Chunk size on RAID arrays

[Danny Cox]

Greg,

On Sun, 2003-07-20 at 14:41, Danny Cox wrote:
> 	One caveat about XFS.  I know of one person who disliked this "feature"
> so much, that he refuses to use XFS.  If, when creating a file, the
> system experiences a reboot (power loss, tripping over the cord, kernel
> bug), the content of that file is zero filled (ASCII NUL). This is for
> security reasons.  I don't remember if it affects the whole file if
> you're just appending at the time of the reboot or not.  Of course, a
> UPS all but eliminates this issue.

	From the XFS FAQ (http://oss.sgi.com/projects/xfs/faq.html): This same
will apply to other metadata only journalling filesystems.  The current
Linux kernel VM will write out metadata after 1/60th of a second, and
the data after 30 seconds.  So the possibility of losing data when
unplugging the power within 30 seconds is quite large.

	Also, for the best performance, see the FAQ question regarding "very
bad dbench (etc.) results with XFS":

	mkfs -t xfs -l size=32768b -f /dev/device

which creates a larger logspace.  Mount with

	mount -t xfs -o logbufs=8,logbsize=32768 /dev/device /mountpoint

this really helps with metadata intensive applications (lots of
creation/deletion of files/directories).

-- 
kernel, n.: A part of an operating system that preserves the
medieval traditions of sorcery and black art.

Danny

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