File fragmentation

Rob Bosch robbosch at
Sun Aug 6 15:50:47 GMT 2006

I've been running some tests on files created by rsync and noticing
fragmentation issues. I started the testing because our 5TB array started
performing very slowly and it appears fragmentation was the culprit. The
test I conducted was straighforward:

1. Copy over a 49GB file. Analyzed with contig (from sysinternals), no
2. Ran rsync and the file was recreated normally (rsync options were -ruvi
--times --no-blocking-io --compress-level=9 --bwlimit=0 --stats --delete
3. Resulting file had almost 12000 fragments. 

It doesn't really surprise me since rsync grabs blocks as it needs them for
the new.  I was wondering why rsync doesn't preallocate the space like copy
or other utilites do under Windows. This would insure you have the space to
create the new file plus it would reduce fragmentation since rsync would be
writing to a pre-allocated file space.


I am running the cygwin version of rsync provided be Tev at
<> .  His site is a huge help to those of us running
rsync under Windows.



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