Allocation unit size for a 3TB data drive?

[apav]

Hey guys,

 

Running Windows 7 (and Windows 10 Technical Preview on another drive). Just upgraded to a 3TB WD Black, I initialized it to GPT, but I am wondering what should set my allocation unit size to, default or 64k. I understand what each do (less wasted space vs faster speeds), but I can't determine what would be better for my drive. This is a data drive, it holds all my games, pictures, movies/shows, ect. According to WinDirStat, I do have a lot of large files (1GB to 12GB is my largest file I think), but I also have a lot of smaller files as well. Don't know which would be better for me. Does it really matter?

[failblox]

No it doesn't really matter. I believe it means the size of each 'block' that it breaks your HDD into. So if you have a lot of very very small files, and a large allocation unit size then those smaller files will take up a lot more space than they actually are. I'm not 100% sure about this though so if someone in the LTT community knows, please correct me.

I just choose default every time and I've never had any issues.

 

Edit: I think this link explains what allocation unit size is: http://www.howtogeek.com/180369/why-is-there-a-big-difference-between-size-and-size-on-disk/

[apav]

No it doesn't really matter. I believe it means the size of each 'block' that it breaks your HDD into. So if you have a lot of very very small files, and a large allocation unit size then those smaller files will take up a lot more space than they actually are. I'm not 100% sure about this though so if someone in the LTT community knows, please correct me.

I just choose default every time and I've never had any issues.

Thanks, well I know there wouldn't be any issues with either, I guess I'm just wondering if 64k would make my HDD noticeably faster, and if there would be noticeably more space being used compared to 4k (with the exactly the same files).

[failblox]

Thanks, well I know there wouldn't be any issues with either, I guess I'm just wondering if 64k would make my HDD noticeably faster, and if there would be noticeably more space being used compared to 4k (with the exactly the same files).

I think with RAID it can make a difference though, but don't quote me on that.

[apav]

By the way here is the SMART data for my new drive, can you please check and see if anything looks worrisome? I don't know about Read Error Rate or Reallocated Sectors Count (don't quite understand what each value associated with the attribute name means). Thank you!

[Captain_WD]

Hey guys,

 

Running Windows 7 (and Windows 10 Technical Preview on another drive). Just upgraded to a 3TB WD Black, I initialized it to GPT, but I am wondering what should set my allocation unit size to, default or 64k. I understand what each do (less wasted space vs faster speeds), but I can't determine what would be better for my drive. This is a data drive, it holds all my games, pictures, movies/shows, ect. According to WinDirStat, I do have a lot of large files (1GB to 12GB is my largest file I think), but I also have a lot of smaller files as well. Don't know which would be better for me. Does it really matter?

 

Hey apav,

 

I would leave the allocation unit size to default since you have both small and large files. If you change it to larger or smaller value, either the large or the small files could get corrupted or have other problems. You already know what's the main difference in the allocation unit sizes and this won't result in a noticeable difference in your capacity or transfer rates with that 3TB drive. 

 

Which diagnostic program are you using? The S.M.A.R.T. status looks ok to me. I would suggest trying WD Data Lifeguard Diagnostic tool since it's the native tool for that drive and will give you more accurate results. Here's a link: http://support.wdc.com/product/download.asp?groupid=810&sid=3〈=en.

 

Happy Holidays!

 

Captain_WD.