2 question about XFS fragmentation and _fsr

Janos Haar
2011-04-11T17:35:42Z

Hello list,

First, please CC me because i am not on the list.

Question 1:
I am working in a data recovery company, and we are using one 3TB RAID
storage with XFS to store the recovery cases in image files.
For spare a lot of space, usually we are imaging only the used spaces of the
filesystems. (for example 1TB system drive wich have only 80GB data inside
but needs to be bootable, the image is similar like Ghost images)
But this makes a lot of sparse files, wich right should be this way.
Some cases are done and we are closed (image can be deleted), and some needs
to store for long time.
In the result, actually we have >6TB images on the 3TB disk, wich is 97.9%
fragmented.
Basically the sparse RAW disk images should be more faster accessible than
the original drive, because this is 4disk raid, instead of one, AND the head
don't need to travel through the empty space of the drive...
But actually we are proud if we can read or write in 8-10MB/s! :-D
I have started to read about xfs_fsr but there is almost none information,
how it is _really_ working, and i am doubt about this will try to fill up
all of my images, and therefore fail to do any improvement, or this will do
the right job and will re-organize the sparse files again.
The XFS_FSR can be good for me or not?
If not, i suggest to implement an option to do sparse fles on the result or
not in the next releases...
I will say a huge thanks in the end. :-)

Question 2:
One of our customers have one storage wich is exactly the same like the one
wich is described on the Q1, but only used for samba storage for storing
media files (big files.)
I am sure, there is no torrent or similar, and i have told to the customers
on the beginning "don't write more files parallel, to avoid fragmentation",
but today the storage is >95% fragmented.
The customer sad, he only does file write one by one, and nothing more.
How can this be?

Thanks for your attention,

Best regards,
Janos Haar