Defragmenting with low priority

[Nick]

Hi,
I wanted to set up my computer to defragment
often at low priority, so I made a batch file
with this command in it

start /low defrag c: /f

and placed the batch file in scheduled tasks.
However when defrag runs, although it is low
priority it creates the process dfrgntfs.exe
to do the actual defragmenting, so that process
ends up normal priority. Windows doesn't allow
running dfrgntfs.exe straight off. Any ideas
for defragging at low priority?

 

[David Jones]

I'm not sure that there's much benefit to doing this.
Defragmenting very often doesn't really give much of a
performance gain.

Also, even at low priority, the act of lots and lots and
lots of disk read/writes is what slows the machine down
while defragmenting. Let's say the machine has a small
idle period, like a fraction of a second, before a higher-
priority process wants CPU time.
The defragger uses that and tells the disk to read/write,
etc. Disks are VERY slow compared to the CPU and the
motherboard bus. A higher priority process that needs to
do its own reading/writing may end up getting blocked
waiting on the defrag's read/write, and therefore be
slowed down.

The other thing here is that if you have lots of other
things running while you defragment, the defragmenting
may take MUCH longer, and have to restart many times,
depending on if the other things running are writing or
moving things on disk, therefore invalidating what the
defrag process is trying to do.

For the time it takes to defrag modern drives, and the
potential performance gain, it's just really not worth it
to do it very often.

 

[Greg Hayes/Raxco Software]

David,

Please see
http://www.microsoft.com/technet/tr...chnol/winxppro/evaluate/xpperf.asp?frame=true

Microsoft considers fragmentation to be such an issue that it is the first
thing listed under Evaluation Issues.

- Greg/Raxco Software
Microsoft MVP - Windows File System

Disclaimer: I work for Raxco Software, the maker of PerfectDisk - a
commercial defrag utility, as a systems engineer in the support department.

Want to email me? Delete ntloader.