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Cluster (allocation unit) size for NTFS in Windows 7

Last response: in Windows 7
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January 25, 2011 12:24:23 AM

Hi,

I am using Win 7 Pro x32 and have partitioned my hard drive into two NTFS partitions. One is for my Windows other one is for my files and personal documents. I'd like to know how to format the partitions in terms of cluster size. I read a lot of articles which didn't actually answer my question - what are the differences between formatting with a big and small cluster size, and how does all that influence the overall performance. I should also mention that I am willing to sacrifice some bits and bytes from my partitions, if needed, as long as I could somehow increase performance. Also, I noticed that the standard Windows 7's formatting dialogue allows to format a partition only with a limited size of clusters compared to trying to format a partition using software such as Acronis Disk Director or Paragon Hard Disk Manager where I was able to format with a much greater cluster size. What to do, what to do...? You could save the small talk such as - 'small cluster size wastes less disk space but works slower, and vice versa, greater cluster size wastes more space but gives better performance'. Is there anything more to it than that, any other pros or cons?

Cheers!
SV
a b $ Windows 7
January 25, 2011 5:45:13 AM

I'll be very frank with you: I don't believe it's worth the effort worrying about something like this. I'd be very surprised if you are able to notice the difference in real-world terms. Also, why partition in the first place? Partitioning makes sense if you have two operating systems, but why separate Windows from your files and documents?
a b $ Windows 7
January 25, 2011 7:20:45 AM

Let Windows worry about cluster size; it'll make a better job of it than you could. The only exception that I would make is if you were tuning a high-performance database server and had collected the appropriate performance data.

If you really are determined to do this, read this article, which explains the technicalities.
Related resources
January 25, 2011 8:34:07 AM

Herr_Koos said:
I'll be very frank with you: I don't believe it's worth the effort worrying about something like this. I'd be very surprised if you are able to notice the difference in real-world terms. Also, why partition in the first place? Partitioning makes sense if you have two operating systems, but why separate Windows from your files and documents?



Well, the only reason I make 2 separate partitions is because I was told to always have my private files on a separate partition, because if a virus struck my computer, for example, then it would most likely strike the partition where Windows is installed. I'm not sure if this is true, but it's just a habit I developed. Is it wrong to do so?
a b $ Windows 7
January 25, 2011 8:54:11 AM

Data can be copied freely from one partition to another, so I cannot imagine how this would offer any additional protection. If you are worried about losing critical files and documents, make regular backups and store them in a safe location.
January 25, 2011 9:33:23 AM

Herr Koss,

I multi-partition drives in order to isolate the OS, games, movies, miscellaneous downloads, and the swap file. Why? Because when dealing with systems with 100's of GB, perhaps even several TB worth of storage, it's a helluva lot easier to defrag the specific partition you just installed 15GBs or more worth of game data onto than it is to have to defrag every piece of data on your PC at once. It also allows me to create a partition copy/back-up image of the OS install itself, post-Windows authentication. This alone lets me perform rather quick OS refreshes without having to format everything. Thus I never lose, nor do I need to back-up, all the data stored on the other partitions.

To each their own, though...
a b $ Windows 7
January 25, 2011 10:10:23 AM

Fair. But it's not something your average home PC user will do, or indeed worry about.
January 29, 2011 12:30:19 AM

OK, so after all that was said, what should I do with my 1TB external hard drive from WD. What cluster size should it have. On it I'm storing all sorts of files... from small ones to big ones...?
a b $ Windows 7
January 29, 2011 3:54:57 AM

Let. Windows. Decide.
April 24, 2011 5:03:51 AM

RazberyBandit said:
Herr Koss,

I multi-partition drives in order to isolate the OS, games, movies, miscellaneous downloads, and the swap file. Why? Because when dealing with systems with 100's of GB, perhaps even several TB worth of storage, it's a helluva lot easier to defrag the specific partition you just installed 15GBs or more worth of game data onto than it is to have to defrag every piece of data on your PC at once. It also allows me to create a partition copy/back-up image of the OS install itself, post-Windows authentication. This alone lets me perform rather quick OS refreshes without having to format everything. Thus I never lose, nor do I need to back-up, all the data stored on the other partitions.

To each their own, though...



That's what i am thinking as well.
For backup and restore as well as re-installation potential in microsoft platforms, it is better to have an isolated partition for OS itself.
October 22, 2012 5:47:33 AM

@RazberyBandit EXACTLY right!! You said it much more politely than I probably would have, lol. Granted, the typical user would never know such a thing is possible, but for elite users, enthusiasts, and those who like to "refresh" (i.e. do a clean install of) Windows this is DEFINITELY the preferred method.

Fortunately Windows is smart enough to manage the cluster sizes itself to optimize performance, so that's not really something you need to worry about. However, when it comes to having your system run at peak performance, it is certainly wise to partition and separate data from OS and apps. :)  This is particularly the case if you want to leverage the performance benefits of SSD without having to pay out the nose for a larger capacity one, and yet have a nice disaster recovery plan in case of failure by making a partition on your HDD for regularly cloning your OS and apps from the SSD.
a c 215 $ Windows 7
October 22, 2012 5:30:41 PM

stamenvalchev said:
Also, I noticed that the standard Windows 7's formatting dialogue allows to format a partition only with a limited size of clusters compared to trying to format a partition using software such as Acronis Disk Director or Paragon Hard Disk Manager where I was able to format with a much greater cluster size.


You might not be able to do this in the windows format GUI, but you can open a command prompt and issue it on the command line.

format c: /fs:ntfs /q /a:<allocation unit size>

Do a format /? for help.

As others have said, it's best to let windows manage it.
September 9, 2013 4:46:12 AM

Herr_Koos said:
I'll be very frank with you: I don't believe it's worth the effort worrying about something like this. I'd be very surprised if you are able to notice the difference in real-world terms. Also, why partition in the first place? Partitioning makes sense if you have two operating systems, but why separate Windows from your files and documents?


Why? Easy, because no matter how diligent you are, Windows WILL ALWAYS need to be reinstalled about once or twice a year. Doesn't matter if you don't install/remove many programs. Doesn't matter if you use a registry cleaner. Doesn't matter if you use an antivirus. Windows is poorly designed and will ALWAYS slow down. My hard drive has 0% fragmentation. I clean my registry regularly. I clean temp and cache files regularly. Still Windows slows down.

So if you have to reinstall windows and your data is on a separate partition then you don't have to think about backing up and restoring the data after each re-installation.

Another poster said this is something your average home user wouldn't know how to do, I agree, and it is a shame that Windows, Apple, and all the other OSs don't do it for the user automatically. Pathetic actually. I as a user shouldn't even have to think about backing up my user settings and I shouldn't have to get a third party app to back them up. Your user setting should be easily stored and moved. Buy my experience has been that even with how smart programmers are they are really stupid when it comes to simple things like this.

Getting back the the cluster size. So if we should let Windows do it then my suggestion is that Windows shouldn't offer any options for cluster size and it should be hard to find like so many other things are hard to find. Only someone who needs to and knows why they need to should be able to find this setting. But again programmers will make it difficult to find things you really need an want to change and yet make it easy to find something like cluster size.
!