Data Drive - Allocation Unit Size

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budec

Gawd
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Jul 10, 2002
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I have my main Windows OS drive on an SSD.

I'm adding a second HDD for Games and data (Movies and Music). Would I get any performance increase if I changed the "Allocation Unit Size" [during format] to a higher value than default? It'll be NTFS.

Most of the files on this drive will be fairly large (movie is 1-5 gigs, most game data files are pretty huge also). I'm not concerned about "wasted space"; the drive is 1 TB and only need 300 gigs or so for games.

I'm considering 64KB (largest windows offers).
 
Would I get any performance increase if I changed the "Allocation Unit Size" [during format] to a higher value than default?
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I never knew what that was for or what it could do so I never messed with it.

Hey Joe or Red, what's it for and is there ever a need to screw with it?
 
well, I did some benchmarks here. There is about 10-25% increase in performance (both read and write) with 64KB over default when file is 64KB or greater (which is majority of my game files).

files above 64kb: 19029
files below 64kb in size: 2513 (configs, shortcuts, etc)

HDTune shows quite a bit faster in 64Kb or greater file chunks.
benchmark feature in Just Case 2 show quite a bit of increase too.
It's hard to accurately measure it, but levels seems to load faster in other games too.

I'm not sure "Leave it alone" is a very compelling argument.
 
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It's your hardware, do what you want with it, but if you ask people the same question, more often than not you're going to get the leave it alone response simply because the defaults almost always offer the best results.

It's that "seems to load faster" thing that gets ya...

"How fast is fast?"
 
budec said:
I'm not sure "Leave it alone" is a very compelling argument.
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I am not sure if this is still the case but using non-default block size used to remove your ability to use filesystem encryption, compression or use the defragger.
 
It's that "seems to load faster" thing that gets ya...

"How fast is fast?"
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In that case, I was timing it by hand [stop watch] loading TF2 levels. Default was an average of ~7 seconds and 64Kb was tad bit under ~5 seconds. The "seems" part is obviously there could be human error in the timing. The other benchmarks (HDTune, file read/write, etc) all had hard numbers and ranged between 10-25% faster with 64Kb on files >= 64Kb in size and within 5% of files <64Kb)

simply because the defaults almost always offer the best results.
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For a normal average file system with normal average files; sure I can buy that. But like I said, this is going to be primarily very large data files and OS files are on different disk. I'm not sure applying that one liner is the best in all cases forever and without exception.
 
drescherjm said:
I am not sure if this is still the case but using non-default block size used to remove your ability to use filesystem encryption, compression or use the defragger.
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Thanks for the info. No reason to use encryption and compression on this drive, but good to know for future use. I'll test defragger when I get home.
 
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