Regardless of how many Cloud Shells have been opened, only one VM is created at a time. All of the opened Cloud Shell windows are automatically connected to the same VM.
You can have a maximum of 5 Shell windows open at the same time.
If the Cloud Shell windows remain inactive for 45 minutes, or after you close the window 15 minutes later, the Cloud Shell will release the VM instance. When you open the Cloud Shell again, a new VM is created.
The Cloud Shell provides you with 10 GB of temporary storage. You can store your files in the
/home/shell directory, but the directory will be reset when the VM is released. You can choose to mount a storage space to implement permanent storage. Whenever you open the Cloud Shell, it automatically loads your files.