Defrag RAID volumes?

[OFaceSIG]

Other then vista/7 which I've read due some internal defragging do we need to defrag RAID volumes?

I run in two 400GB barrcuda 7200.10s in RAID0 and I'm wondering if I should even bother defragging.

 

[drozenski]

Yes, We run multiple flavors of raid here at work and at some point they all need to be defraged.

 

[BENN0]

This has nothing to do with RAID though has it? Fragmentation is a filesystem problem.

 

[novadude]

This has nothing to do with RAID though has it? Fragmentation is a filesystem problem.

correct, although it will be very interesting to see what happens in the future with larger HD's. When I switched from the windows defragger to defraggler to get from the 10% fragmentation the windows defragger leaves down to 0% fragmentation took 10 hours on a 5x1tb RAID5 array. I can't imagine doing the same on a low RPM 5tb hdd, so hopefully filesystems improve their handling of files.

 

[keenan]

correct, although it will be very interesting to see what happens in the future with larger HD's. When I switched from the windows defragger to defraggler to get from the 10% fragmentation the windows defragger leaves down to 0% fragmentation took 10 hours on a 5x1tb RAID5 array. I can't imagine doing the same on a low RPM 5tb hdd, so hopefully filesystems improve their handling of files.

Most modern filesystems do pretty well. NTFS isn't great, but it's not too bad.

If you do a regular scheduled defrag with something like MyDefrag it really doesn't take all that long. It's just the first run where most of the files on the disk have to be moved that takes forever.

 

[novadude]

Agreed, defrag tools seem to have their own way of dealing with files and beliefs on where they need to go so the first time running it is always spent watching it do the stupidest damn things with your data. Oooh, the first fragment of this tiny file is at the beginning of the disc so I'm going to fully fragment two terabytes of data while rearranging it to fit the rest of that 150kb jpeg into that space.

 

[Magnetoman]

Fragmentation is a filesystem problem.

+1.
Windows sees the RAID volume as a single logical volume; any distinction wrt to the elements of the array is made only at the controller level IIRC.

As for defragging large volumes, auto defraggers FTW....just install and forget. Manual defrag is / should be a thing of the past...self 'maintaining' systems are the way to go.

NTFS does not prevent fragmentation all that well; even a clean install of windows on a freshly formatted volume will result in plenty of fragments. I believe some of the 'nix FSs have better space allocation algorithms that avoid fragmentation until the drive is nearly full unlike NTFS?

 

[r_shortt]

I still use windows defrag on my file server at home. If your cheap and don't want to buy a product to auto defrag simply create a batch file what contains

Defrag.exe c: -f

Then use the scheduler to run it as ever often that you want. My large raid 5 array gets defraged every second day at like 4am. Granted not much change occurs with the array in 24 hour timeframe

 

[keenan]

MyDefrag is free and way better than the built in tool.

 

[novadude]

I still use windows defrag on my file server at home. If your cheap and don't want to buy a product to auto defrag simply create a batch file what contains

Defrag.exe c: -f

Then use the scheduler to run it as ever often that you want. My large raid 5 array gets defraged every second day at like 4am. Granted not much change occurs with the array in 24 hour timeframe

The problem with that is is quits at 10% fragmentation and calls it done.

 

[Seraphic]

Do you need to defrag a raid if it is a non os drive?

 

[keenan]

Do you need to defrag a raid if it is a non os drive?

You never need to defrag any filesystem. RAID is no different from a regular disk as far as filesystem fragmentation is concerned... Whether or not it's really necessary for decent performance depends on other factors.