[mythtv-users] [OT] how do you defragment a xfs formatted LVM?

Marc Nicholas marc at geekythings.com
Mon Dec 13 23:34:19 UTC 2004


You don't really need to worry about log/journalled file systems with 
regard to fragmenting. Bear in mind that XFS is a fully 64-bit file system 
and was designed from day one to address 9 exabytes!

Now, there are nice things applicable to Mythtv that XFS has or could be 
taken advantage of:

- Huge single file size. We're talking 16 or 64 terabye file sizes on even 
the oldest implementation on Linux.

- XFS supports "realtime" allocation. Rather than using the normal tree 
structure, you can create a subvolume that is better suited to the 
predictability that realtime A/V applications require. I suspect that SGi 
(the originators of XFS) did this so they had a file system capabile of 
serious Video-on-Demand (VoD) applications for cable companies.


  -marc

On Mon, 13 Dec 2004, Chris Petersen wrote:

>> Should I be performing some type of defragmentation on my LVM? The drive
>> seems to be thrashing around quite a bit more recently and fragmentation
>> comes to mind from my windows experience.
>
> afaik, none of the *nix filesystems need to be defragmented.  they're all 
> pretty good about keeping fragmentation down below 1%.
>
> "thrashing around" could just be the filesystem shuffling things around to 
> prevent fragmentation.  or maybe they just hit some kind of "full" threshhold 
> that ends up with more noisy operations.
>
> -Chris
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