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GlobalCluster.512.DAT RRS feed

  • Question

  • Hi All

    I've noticed that the file GlobalCluster.512.dat on my WHS m/c has a size in excess of 14GB; I thought file sizes were limited to 4GB before a new additional file was created

    ie Data.4096.0.dat,  Data.4096.1.dat etc

    Any comments would be appreciated

    Friday, September 4, 2009 9:14 AM

All replies

  • Where is the file located on your machine? I don't have such a file in my backup DB folder (Only GlobalCluster.4096.dat) which in my case is less then 4GB
    Friday, September 4, 2009 11:47 AM
    Moderator
  • Hi Brubber

    it's in the normal database folder D:\{00008086-058D-4C89-AB57-A7F909A47AB4}.
    I should mention that WHS is storing 243GB of backups from 10 of my computers.

    regards
    Friday, September 4, 2009 12:47 PM
  • OK, like I said no such file in my backup DB folder, so can't really help you any further.

    I agree 14 GB is huge. Are you sure it's not 1.4 GB?
    Friday, September 4, 2009 1:13 PM
    Moderator
  • Hi

    actual size quoted now in D:\folders\{00008086-........} is 14,094,652,928 Bytes.

    I also have the same folder as you - GlobalCluster.4096.dat.

    Thanks for the help anyway
    Friday, September 4, 2009 1:32 PM
  • GlobalCluster.512.dat is a valid file; it's created when you back up a computer that has an NTFS partition with 512 byte clusters. You probably have one or more computers (or disks, anyway) that originally were formatted with FAT32, but were converted to NTFS. When you do the conversion Windows won't change the cluster size on the disk, so you wind up with an NTFS disk with 512 byte (or other size) clusters, instead of 4096 byte clusters (the NTFS default). You can also wind up with 512 byte clusters in other ways, but that's the most common...

    Note that this isn't a data file; it's an index and there's only one per cluster size as far as I can tell.

    I'm not on the WHS team, I just post a lot. :)
    Friday, September 4, 2009 3:02 PM
    Moderator
  • Hi Ken

    thanks for the info but going back to my original question, why is this file so big & appears to be getting bigger?  Is there a limit on its size & if so what happens when the file size reaches this limit?
    Friday, September 4, 2009 3:27 PM
  • As I said, only one is created as far as I know (I only have one virtual machine with a converted FAT32 disk, so I can't really test very much). It's as big as it needs to be to hold an index of all clusters in the 512 byte segment of the database. Note, also, that there are 8x as many clusters in that segment of the database for a given amount of data, as a single 4096 byte cluster is as large as 8 512 byte clusters. Using my backup database as an example, which is just under 1/2 TB, my GlobalCluster.4096.dat is around 3.5 GB (I think; I'm not home). That would be more like 28 GB if all my computers had 512 byte clusters.

    As for limits on file size, Microsoft hasn't discussed any with me. I will see what I can find out, however. (No promises here; if Microsoft chooses not to share the information, there will be nothing I can do but say that. Likewise if they share information with me but say "This is under NDA"...)

    My thought is that there is no immediate problem, and no immediate reason for worry.

    I'm not on the WHS team, I just post a lot. :)
    Friday, September 4, 2009 3:37 PM
    Moderator


  • Thanks Ken & Brubber
    Friday, September 4, 2009 5:16 PM