Disk Fragmentation

[Steve Loudermilk]

Reply-to: slouder%pernod at note.nsf.gov (Steve Loudermilk)


I am involved in a local discussion about the benefits of "compacting" the
information on our disks regularly.  By compacting I mean dumping to a
different device, running "newfs" and then restoring a file system.

One school of thought says this is necessary and should be done fairly
frequently to avoid excessive fragmentation and inefficient disk I/O.

The other school of thought says it isn't necessary because of the way 
the Berkeley "fast file system" (BSD 4.2) handles assignment of
blocks and fragments when a file is stored.  

Our system is a Vax 11/785 with six ra81 disk drives, running Ultrix 2.3.
We are currently using a block size of 8192 and a frag size of 1024
for all file systems except one, where we have 4096/1024.  All file
systems are running with at least 12% free space.  

Should I worry about fragmentation?  If so, is dumping and restoring
the best solution?

Thanks in advance,

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Steve Loudermilk			Internet:  slouder at note.nsf.gov
Integrated Microcomputer Systems Inc.	Phonenet:  (202) 357-9648
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