What is the default allocation unit size in XP using NTFS, and what should I set it to if the default is not the best?

[Ronstang]

Title kind of says it. I need to format my other partitions now that XP PRo has been cleanly installed. I'm using NTFS and under formatting I have the option to choose the allocation unit size. If I choose 512 bytes I won't lose as much drive space when there are a lot of small files on my system but will this setting have a negative impact on performace? I don't know enough about this to make a the decision without some input.

What is the default allocation unit size, and should I just leave it be?

Thanks,

Ron

 

[SharkB8]

Default cluster size is 4k. No need to change it unless you are doing something very specific that requires a different cluster size. What that would be I don't remember but that has been discussed here and doesn't apply to most people. Leave it at default settings.

 

[Lord Evermore]

Smaller cluster size gives better performance with lots of small files. Larger cluster size is better if you use mostly large files. I set mine to 16K, but since it's only a data storage drive and I didn't benchmark anything, I don't know if it's performing any different than with other cluster sizes. Most likely on your OS partition or a partition where you're installing applications, you're going to have such a mix of large and small files, that the default will work fine. If you've got a partition where you're storing mostly MP3's and/or video files, then even a 32k or 64k cluster size might be good.

By the way, 4k is only the default after 2GB, so it's possible he'd run into a smaller cluster size.

I stopped worrying about loss of space due to slack/empty space from cluster size and file size differences back when I moved from a 2.1GB drive to a 10GB drive. At this point, it's not worth worrying about it. There's hardly any files that are part of applications anymore that don't take up at least 2 or 3 clusters even at 16k or 32k, so the proportion of lost space has actually gone down over the years.