NTFS compression heavyly increases file fragmentation

[Frank]

Hello,

how can I prevent a file from being fragmented when I use NTFS compression?

I compressed a file on a completely defragmented volume (Windows XP Pro SP2
4K Cluster size on a 60GB volume) and copied new files to it. In each case
the files get heavyly fragmented (A contiguous 40MB Microsoft Access
database file was splitted in about 600 fragments).
I used the Sysinternals Contig utility
(http://www.sysinternals.com/utilities/contig.html) to analyze the
fragmentation.
Is there a tweak to tell the filesystem to take more care of fragmentation
when compressing files? The "fsutil behavior set" command does not offer
such an option.


Kind regards,

Frank

 

[Al Dykes]

Hello,

how can I prevent a file from being fragmented when I use NTFS compression?

I compressed a file on a completely defragmented volume (Windows XP Pro SP2
4K Cluster size on a 60GB volume) and copied new files to it. In each case
the files get heavyly fragmented (A contiguous 40MB Microsoft Access
database file was splitted in about 600 fragments).
I used the Sysinternals Contig utility
(http://www.sysinternals.com/utilities/contig.html) to analyze the
fragmentation.
Is there a tweak to tell the filesystem to take more care of fragmentation
when compressing files? The "fsutil behavior set" command does not offer
such an option.

I'm not sure exactly what you are doing, but putting a file that is
randomly updated, such as your MDB file on compression is a Bad Idea
for reasons that should be obvious; When you insert a record into the
DB the database software doesn't know or care how many bytes the new
data will be, more or less and the number will change every time the
record is updated.

I'm a big fan of NTFS compression and have used it heavily but it
isn't magic.

 

[Frank]

Hello Al,

MDB was just an example. The MDB I've used has a read only attribute because
it only contains reference tables that are linked from other non-compressed
MDB's.
The fragmentation problem is not limited to MDB files.


Regards,

Frank