Change cluster size

Hi, I’ve trying to increase the cluster size of my system partition using different programs (norton p.m., paragon and some others) and procedures (windows xp installed and without windows) but everytime I’ve tried it windows didn’t start. I’ve just got a single message “error reading hard disk”. Formating with the windows installer solved the problem but again a 4kb cluster size.

So i’d like to know if there is safe way to change the size on a boot partition.


hi, maybe this article will help or at least give you a start

[B]The maximum default cluster size under Windows XP is 4 kilobytes (KB)[/B] because NTFS file compression is not possible on drives with a larger allocation size. The Format utility never uses clusters that are larger than 4 KB unless you specifically override that default either by using the /A: option for command-line formatting or by specifying a larger cluster size in the Format dialog box in Disk Management.

it looks like you have to change it using one of the two methods listed. not sure if third party programs will work.

Change Increase Check Windows XP NTFS Cluster Size

If you have the same situation as me and are simply trying to increase the cluster size on a Windows XP partition (up from the default of 4k), after much searching and trial and error
here is how I successfully did it:
(First back up all data or better yet use Norton Ghost 12 and back up the total partition or drive. My C: drive is around 300Gb with about 30Gb of applications, files, operating system, documents, photos, movie clips, etc. and it backs up in about 16 minutes to a USB external drive and restores completely in about 11 minutes)

Next, you will need a utility to actually increase the cluster size, such as Paragon, PartitionMagic, Acronis, etc

Here is where I had problems…every forum post recommended PartionMagic
to do this which can be accomplished by (in PartitionMagic) going to Partition>Advanced> Change cluster size
After about 2 hours it finally finished.
What resulted was an error message of “Disk read error” every time I tried to re-boot into Windows. In fact, my system was crashed. It would not boot at all. I tried FIXMBR and FIXBOOT and some other drive utility to fix it and still nothing.

I restored my drive with Norton Ghost 12 (bootable CD) as mentioned before ( I was up and ready to roll in about 11 minutes, absolutely nothing lost…except my time) and tried PartitionMagic’s “Cluster resize” again. Same thing. Unbootable PC.

I happen to have a bootable CD of Acronis Disk Director Suite 10 from when I used it for something last summer. (Get the trial, if you want to try it HERE )
I booted with it, and lo and behold, it ALSO has a “Cluster resize” feature. I set my cluster size to be increased from 4k to 64k and it finished in about 3 minutes.
I thought something had to be wrong, since it finished so fast, but it booted into WinXP just fine and the cluster size was now 64k!

Couple of notes:

  1. You can no longer use NTFS file compression if you raise cluster size above 4k.

  2. At least 2 ways to check the cluster size used by a drive:
    a) Run WinXP built-in Disk Defragmenter, select the drive, Analyze,
    then View Report. (cluster size is 2nd item in top window)

    b) Type chkdsk at a command prompt. For example, to see the cluster size of D:,
    C:\Docume~1\Cetus>chkdsk d: (and hit the Enter key), where it
    says “____ bytes in each allocation unit,” that is the cluster size.

  3. You can use Acronis to decrease the cluster size as well as increase it

  4. This may matter a lot or not much at all, but my specs are: Windows XP installed on drive C:, which is a RAID 0 array of (2) WD Raptor 150Gb Serial ATA (SATA) drives. My drive D: is a Seagate (SATA) 7200.10 320Gb drive. My mobo is a EVGA NVIDIA 680i SLI. (I have WIndows Vista Home Premium installed on the D: drive and I dual-boot, but that has nothing to do with this “Cluster size” issue, AFAIK

thanks for that Cetus35