Freeware defragmentation for RAID arrays?

paradigm · 20 Dec 2008 at 11:24

I've never really managed to defrag my system, given that most freeware utilities (like defraggler) simply do not have the intelligence in the programming to maintain RAID integrity whilst defragging files.

Does anyone know of a RAID specific (I'm using a RAID-5 array if it matters) defragmenting utility for Windows (x64)?

Cheers.

vertica · 20 Dec 2008 at 13:26

I've asked this before, as using defraggler it appeared (from the block chart) to move all the data to one disk

However when i queried this on here i was told that it shouldn't matter as the fragment splitting should be done at a hardware level and is invisble to the OS/software, but i'm still doubtful...

if you google it, you'll find it appears to be one of those things where no-one has a definative answer either way.

I did however find that Auslogic's defragmenter did a very good job, as on the block diagram there was still a clear divide of data acroos what i guess is the two discs. (data gets defagmented to the begining of the chart and to exactly halfway through) but again whether this is the raid or not i honestly cant say!

paradigm · 20 Dec 2008 at 14:05

Just tried that, certainly shows no "split" where my drives (6 of them) are.

Still pretty certain that no freeware utilities exist that can maintain the integrity of RAID5.

Greenlizard0 · 20 Dec 2008 at 16:02

Not sure on the answer to this, but how does JK defrag do?

Also vertica, what do you mean by block charts?

PistolPete · 20 Dec 2008 at 17:24

I'm a little confused.

If you have a number of drives in RAID5 then surely the RAID controller should be maintaning the integrity as the OS see on the logicial drives configured on the RAID controller, not the physical disks?

Or am I missing the point of your problem??

Glaucus · 20 Dec 2008 at 17:29

I use defraggler for raid 1, doesn't seem to break anything. As said before it shouldn't be handled by the program.

paradigm · 20 Dec 2008 at 18:24

PistolPete said:
I'm a little confused.

If you have a number of drives in RAID5 then surely the RAID controller should be maintaning the integrity as the OS see on the logicial drives configured on the RAID controller, not the physical disks?

Or am I missing the point of your problem??

The problem is that if for example a RAID5 array has a 1GB file split over 4 disks (to quarter the seek and quadruple the read speed - yes theoretical maximums, I know it won't happen IRL), defraggler et al just see the file as fragmented, and moves it to not be.

So whilst it won't break anything, it *could* technically hinder performance.

philjohn · 20 Dec 2008 at 22:23

paradigm said:
The problem is that if for example a RAID5 array has a 1GB file split over 4 disks (to quarter the seek and quadruple the read speed - yes theoretical maximums, I know it won't happen IRL), defraggler et al just see the file as fragmented, and moves it to not be.

So whilst it won't break anything, it *could* technically hinder performance.

Problem is, all of these defrag utilities (including Diskeeper who originally requested them after maintaining a fork of NT for their enterprise customers) use the same NT Kernel commands to do their work, one gets a map of the filesystem and the other performs atomic moves of files.