AZCopy concurrent connection RRS feed

  • Question

  • I need to lower the amount of concurrent connections when using az copy since it attempted to take all my bandwidth. I was having trouble finding out what the default is. I found that the max is 512.

    Any one know what it is?


    Paul Glickenhaus

    Tuesday, October 4, 2016 1:24 PM

All replies

  • Hi Paul,

    Thank you for posting here! We are happy to assist you.

    "Number-of-concurrent-operations" Specifies the number of concurrent operations.

    AzCopy by default starts a certain number of concurrent operations to increase the data transfer throughput. Note that large number of concurrent operations in a low-bandwidth environment may overwhelm the network connection and prevent the operations from fully completing. Throttle concurrent operations based on actual available network bandwidth.

    The upper limit for concurrent operations is 512.

    Applicable to: Blobs, Files, Tables


    Sumanth BM

    Tuesday, October 4, 2016 6:37 PM
  • Thank you for the reply.    I am trying to find the default connection.  I need to lower the concurrent connections since when I run the a file copy it takes all the bandwidth.


    Paul Glickenhaus

    Tuesday, October 4, 2016 6:42 PM
  • Paul - use the NC switch...

    as per https://blogs.msdn.microsoft.com/windowsazurestorage/2013/03/31/azcopy-using-cross-account-copy-blob/ (a bit stale - but, as far as I understand, this still applies)

    This option allows you to specify the concurrent network calls. By default, when you upload files from local computer to Windows Azure Storage, AzCopy will initiate network calls up to eight times the number of cores this local computer had to execute concurrent tasks. For example, if your local computer has four cores, then AzCopy will initiate up to 32 (eight times of 4) network calls at one time. However, if you want to limit the concurrency to throttle local CPU and bandwidth usage, you can specify the maximum concurrent network calls by using /NC. The value specified here is the absolute count and will not be multiplied by the core count. So in the above example, to reduce the concurrent network calls by half, you would specify /NC:16



    Tuesday, October 4, 2016 9:25 PM