Zephyr Scale Jira DC to Jira Cloud migration

Hi Team, 

I am migrating from Jira DataCenter( three cluster nodes) to Jira Cloud. We use Zephyr Scale for test management.  Problem is every time we start the migration, using JCMA (what to migrate ) option, when it comes to Zephyr scale app, one of the server goes down with memory full. This is now the second instance one of the servers has gone down. These nodes have around 40 GB free space. Not sure how much space now this app needs to complete the migration. Is there a way to check the same. It has become a blocker for migration now. 

regards,

Shyam