• This topic has 2 replies, 3 voices, and was last updated October 28, 2019 by Aviv M.

de-duplication on NTFS

  • A user uploaded a bunch (perhaps several hundred megabytes of similar PDF files — drawings) today that may have caused a massive uptick in journal changes. My hypothesis is that the de-duplication on NTFS was creating a lot of extra writes. But I saw a 300 GB growth but there were not that many files. The normal journal size has been about 11 GiB.

    Tried to find sources of deletes or other things to no avail. Is my hypothesis plausible?
    As an aside, our Nimble storage now supports de-duplication so I could theoretically grow the NTFS volume and remove ntfs de-dupe.

    better phrased, can a few gigabytes of files with some potentially common data, create an exponential increase in journal size due to de-dupe?

    The  journal size  is not only correlated to that amount of IOs that a VM is generating is a single day:

    Think of it as a buffer file before the IOs are written to the Mirror disks.

    There are additional VPG parameters in consideration that will effect the size – the expected journal history in days – max journal size or if it was set to unlimited.

    For more see the below KB

    Journal Overview, Sizing & Best Practice – Zerto Virtual Replication:




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