Hello,
THis is an interesting issue. First a few things about snapshots. You only want the snapshots to live for the length of time it takes to make the backup and no longer. The reason for this is mainly performance and some times odd networking behavior. Snapshots are a means to safely copy a VMDK that since you have using a snapshot is no longer changing on you. Thereby giving you a safe backup. Once the backup is done you commit the snapshot allowing the disk to change once more.
Okay now that we have covered snapshots, your tools of choice will be to use Veeam, esXpress, VISBU, or vRangerPro to perform backups to a local physical machine. You definitely do not want to backup to a local machine due to the horrible write performance of the VMFS, which will affect data transfer as well.
Also, during the work week you would make delta backups so that the data transfer is minimal. Veeam is one you could use to do this, but it will also create a pseudo virtual disk which you can most likely disable.
So you make local backups of the full VMDK once every so often but after that you make DIfferential backups. THereby transferring even less data throughout the night.
If you use a local backup server you can store a copy of the compressed virtual machine image locally with all associated differentials ready to restore. Then copy those files across the wire every night. I would definitely make a full backup every so often however. This way you have two copies of backups one ready to restore locally and one ready to restore anywhere.
CHeck out a '[Comparison of VI3 Backup Tools|http://vmprofessional.com/index.php?content=esx3backups]' for information on vRangerPro, Veeam, and esXpress.
If you really wanted to you could use the tool from the central office as well, and use differentials most of the time. Once more to limit your data transfer to only what changes. In this case, Veeam may be a code choice as it rebuilds the VMDK so that when you restore, you restore just the VMDK and not a VMDK then a bunch of differentials.
Best regards,
Edward L. Haletky
VMware Communities User Moderator
====
Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.
Blue Gears and SearchVMware Pro Blogs -- Top Virtualization Security Links -- Virtualization Security Round Table Podcast