title: Can multiple Colab notebooks share the same Runtime?
body: <p>In Q1 2019, I ran some experiments and I noticed that Colab notebooks with the same Runtime type (None/GPU/TPU) would always share the same Runtime (i.e., the same VM). For example, I could write a file to disk in one Colab notebook and read it in another Colab notebook, as long as both notebooks had the same Runtime type.</p>
  
  <p>However, I tried again today (October 2019) and it now seems that each Colab notebook gets its own dedicated Runtime.</p>
  
  <p>My questions are:</p>
  
  <ul>
  <li>When did this change happen? Was this change announced anywhere?</li>
  <li>Is this always true now? Will Runtimes sometimes be shared and sometimes not?</li>
  <li>What is the recommended way to communicate between two Colab notebooks? I'm guessing Google Drive?</li>
  </ul>
  
  <p>Thanks</p>