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  • 1.  VMFS block size = access size?

    Posted Sep 06, 2010 04:40 AM

    If I have a block size of something, say 4 MB, will that also be the minimum access size on disk? That is, is it possible to still read or write to VMFS in smaller amounts than the block size?



  • 2.  RE: VMFS block size = access size?

    Posted Sep 06, 2010 04:48 AM

    Yes - VMFS does sub block allocation.

    --Matt

    VCP, vExpert, Unix Geek, Storage Nerd



  • 3.  RE: VMFS block size = access size?

    Posted Sep 06, 2010 04:52 AM

    Hello and thank you for your reply.

    If I understand it correctly the sub block feature is to fit smaller files into one block, to not waste space for small config files for example.

    However, my question is what will happen if I have 4 MB block size and a flat-vmdk file is covering several hundreds of these. Could my IO read/writes to this vmdk still be smaller then the block size?



  • 4.  RE: VMFS block size = access size?
    Best Answer

    Posted Sep 06, 2010 05:00 AM

    Yes - the size of the IO request from the guest is passed through.

    --Matt

    VCP, vExpert, Unix Geek, Storage Nerd



  • 5.  RE: VMFS block size = access size?

    Posted Sep 06, 2010 06:56 PM

    Yes - the size of the IO request from the guest is passed through.

    Great! So it is no real disadvantage with using the largest blocksize?



  • 6.  RE: VMFS block size = access size?

    Posted Sep 06, 2010 07:02 PM