Default Cluster Size Issues

I recently ran into quite the dilemma with my home storage server.  I have a large RAID5 that had 8x 2TB drives.  This gave me a usable capacity of 14TB.  When I had originally started off with just a few drives, this drive volume was formatted with the default windows cluster size of 4k.  That would be all fine, except it would not let me expand my drive past 16TB.

Here’s some info about cluster sizes in a Microsoft environment:

Default cluster sizes for NTFS

The following table describes the default cluster sizes for NTFS.

Volume size Windows NT 3.51 Windows NT 4.0 Windows 2000, Windows XP, Windows Server 2003, Windows Vista, and Windows Server 2008
7 MB–512 MB 512 bytes 4 KB 4 KB
512 MB–1 GB 1 KB 4 KB 4 KB
1 GB–2 GB 2 KB 4 KB 4 KB
2 GB–2 TB 4 KB 4 KB 4 KB
2 TB–16 TB Not Supported* Not Supported* 4 KB
16TB–32 TB Not Supported* Not Supported* 8 KB
32TB–64 TB Not Supported* Not Supported* 16 KB
64TB–128 TB Not Supported* Not Supported* 32 KB
128TB–256 TB Not Supported* Not Supported* 64 KB
> 256 TB Not Supported Not Supported Not Supported

Note * means not supported due to the limitations of the MBR.


I added another 2x 2TB drives to the array and wanted to expand my drive volume for them.  In order to do this, I would have to somehow move to a larger cluster size.  I decided I would like to be at a 16k cluster size since that would allow me to go up to 64TB for a single volume.  In order to do this, I created a new partition on the drive using the new space that was available from the added disks.  This partition was formatted with a 16k cluster size.  I began to copy data off of the old 4k cluster size partition on to the new 16k partition.  After filling up the available space on the new partition, I would shrink the size of the old partition, and then expand the size of the new partition to take up that freed space.  This is a slow process with this amount of data, but since it’s just my home server with no critical data, I couldn’t just backup and restore, and I really didn’t want to have to replace the data.

After a few shrinks and expansions, I finally had all my data on the new 16k partition, and was able to delete the old partition all together and expand the new one to the full drive size.  Now I will be able to add more disks and expand up to 64TB.  To perform my shrink and expand operations, I used MiniTool Parititon WIzard Server Edition 7.1.  I used this tool because whenever I used the windows disk management console, it would always tell me I needed to convert the drive to a dynamic disk.  I wanted to leave the drive a basic disk.

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