What to expect when you copy an environment or template

This article describes what happens when you copy an environment or template, though the main focus of this article is about what happens when you copy an environment from one region to another.


How copying between regions works

The copy process helps to ensure that all copy jobs are treated fairly and that Skytap customers are not affected by the Skytap usage of other customers.

Connections between regions

Skytap uses dedicated connections between pairs of regions that have particularly high traffic between them. The remaining regions are connected by VPN over internet.

Virtual channels

The bandwidth for copy jobs is divided into virtual channels. Each virtual channel is dedicated to the copying of a single VM.

One VM at a time

The environment is separated into individual VMs, which are copied individually using the available virtual channels.

How the copy process works

When you initiate a copy job, the job may not start immediately. If there are other copy jobs already running, your copy job is added to the queue. Skytap adds copy jobs to the queue in the order in which they arrived.

Shared bandwidth for copy jobs
  • Skytap balances the overall queue and the available virtual channels between all of the customers in the queue, depending on what order jobs entered to the queue.
  • If there are more jobs than there are channels, then the VM copies in progress must complete before other jobs may use a channel.
  • When one or more virtual channels are available for your copy job, Skytap copies your environment, one VM per channel.
Copying environments from multiple customers.

What variables affect the copy process

These are the most common factors that can affect the amount of time it takes for your copy job to complete.

The size of your job

Just like any file transfer, the bigger your job, the longer it will take to copy.

Skytap compresses virtual disks during transfer to reduce transfer time.

Copying different sizes of VMs.

Internet congestion

Many copies between regions are sent via VPN over the internet. The transfer speeds for these connections are highly variable. Your copy job may be slowed by internet congestion caused by high volumes of internet traffic.

Peak internet traffic may vary, depending on the time of day or the day of the week.

If your copy job is between regions that use a dedicated connection, internet congestion isn’t a factor, but other Skytap customers may have their own copy jobs in the queue. The overall system load is managed so that a copy job doesn’t degrade the experience of other users and that the workload of other users doesn’t affect the speed of copy jobs.

The number of copy jobs in the queue

Because the channels are shared equitably among all pending copy jobs, the more jobs that are in the queue, the fewer channels there are available, and the longer you might have to wait for an empty channel.

If the queue isn’t crowded, your job may get more than one virtual channel, which speeds up your copy job. In some cases, particularly during low traffic times, your job may get multiple channels.

Copying a single environment when the queue is empty and then sharing the queue with another customer.