[INFO] Operations Used by the vCloud Transfer Space

Today the question came up on one of Jason Boche’s posts about expanding the vCloud Transfer space operations and when that transfer space is used.  I dug through some old emails and located a transcript from a conversation I had asking the same question.  I got the reply below from someone in engineering.

The Short answer: If there’s a large chunk of data to be copied (any virtual machine or media upload or copy), it will go through the transfer space first. The only exceptions are those that can be explicitly checked for and optimized away internally (source and destination is the same datastore, in the same cluster of the same vCenter, stuff like that).  So some examples are:

  • Catalog to mycloud/ catalog to catalog / vApp to vApp / vApp to catalog (SAME Org vDC):   NOT transfer store
  • catalog to mycloud/ catalog to catalog/ vApp to vApp/ vApp to catalog (DIFFERENT Org vDC):   possibly/probably transfer store (depends on Org vDCs and their vCenter+cluster+datastore consanguinity)
  • Ovf/iso uploads: transfer store
  • Import from vCenter (to orgvdc on SAME cluster or vCenter): NOT transfer store
  • Import from vCenter (to Org vDC on DIFFERENT cluster or vCenter): transfer store

The IOPS associated are whatever the network plus the datastore can handle; the usage pattern is almost exclusively bulk sequential writes/reads, as if for a file server that gets a very small number of requests for very, very large files.

About Chris Colotti

Chris is active on the VMUG and event speaking circuit and is available for many events if you want to reach out and ask. Previously to this he spent close to a decade working for VMware as a Principal Architect. Previous to his nine plus years at VMware, Chris was a System Administrator that evolved his career into a data center architect. Chris spends a lot of time mentoring co-workers and friends on the benefits of personal growth and professional development. Chris is also amongst the first VMware Certified Design Experts (VCDX#37), and author of multiple white papers. In his spare time he helps his wife Julie run her promotional products as the accountant, book keeper, and IT Support. Chris also believes in both a healthy body and healthy mind, and has become heavily involved with fitness as a Diamond Team Beachbody Coach using P90X and other Beachbody Programs. Although Technology is his day job, Chris is passionate about fitness after losing 60 pounds himself in the last few years.


  1. Dude, many thanks for responding to my comment on Jason Boches blog. Your the best man! thanks!~

  2. Can you clarify for everyone if the transfer requires enough space for an individual VM or the entire vApp at a time?

    • Harry, I will look into it.  However, since the export is at the vApp level, I suspect it will need the full space for all the VM’s in the vApp.  Depending on the size of the various vApps then you need enough for the largest vApp.  It also exports as VMDK’s, but I think only exports the actual size in use not configured size.  So guessing at the Transfer Space size is still a bit of guesswork.  NAS makes it easy to resize of course as needed.

      • Yeah, I think you’re right, too. And yes, it’s a guessing game with sizing it. haha Thanks 🙂 I just figured that would help everyone to think about that when they’re planning it out (which could also be added to your other blog posting about making sure they partition out the transfer space if it’s local).

        • Yes!  Or add a separate VMDK for transfer all together and set that as the mount point.  Usually we are seeing at least two cells so the shared storage is a requirement anyhow, but point well taken on the single Cell Setup.

    • I did confirm we have to upload/download the whole vApp to the transfer service,
      so we do need enough space for the entire vApp itself.

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