Resize NTFS cluster size without reformat

Posted on 2009-02-21
Last Modified: 2012-05-06
I have a large file server that has a 1.5TB partition that is using about 1TB of the available 1.3TB. The volume is using Shadow Copies, but they disappear each time a defrag runs. I found a MS KB article that explains this is a problem with small cluster sizes. I'm looking for a solution to increase the cluster size to 16k or higher.

The server is running Windows Server 2003 R2 x64, obviously formatted NTFS.

This server is being used for DFS Replication so I don't want to have to go through the process of backup and restore as this triggered complete DFS repopulation last time. Also, backups fail miserably using NTBackup with that volume of data and take forever to get anywhere. They never get past about 650GB.

What tools or options are there for upping the cluster size in NTFS?
Question by:jhalscott
    LVL 16

    Expert Comment

    Natively, you'd have to back up the volume and then reformat, using "/A:16K" before restoring.
    On XP, you could have used Partition Magic to do this without a reformat but that is not advertised as working on Server 2003 - never mind an x64 architecture!
    The following piece of software does various advanced partition things, although I'm not sure if "just" changing cluster size is amongst them:
    Either way, I'd say it's a rather brave thing to do to a live system - and a server at that.

    Author Comment

    I was hoping there was something outside of the reformat. I don't think any third party software operating outside of the OS will work since it most likely won't support the RAID chipset. It is a PERC 5/i in a Dell PowerEdge 2950 III.

    I'm testing using Diskeeper 2009 since it is supposed to have VSS support. I've been running it now for almost 24 hours straight and the Shadow Copies are still present. I had to choose an option to enable VSS support, but so far it looks good.

    Assuming no other options arise it would be worth the cost of the two licenses. I need to not get burned on these two file servers. I normally would let the replication run again if the servers were local to each other, but in this case the servers even over a fast link are abut 150 miles away. Replication would take months.

    Making mental note to always format the file server drives with 16k.
    LVL 2

    Expert Comment

    Acronis Disk Director claims to support RAID and has an option to change cluster size on a volume.

    Accepted Solution

    Cannot be done, closing question.

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