Chris Colotti's Blog Thoughts and Theories About…
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.
Dude, many thanks for responding to my comment on Jason Boches blog. Your the best man! thanks!~
I just wish I had not forgotten until now to post this! 🙂
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.