SQL database virtual machines become unresponsive during replication operation.

Products

• VMware Live Recovery

Issue/Introduction

SQL virtual machines goes to hung state during vSphere Replication sync operation.

Environment

VMware VLSR 9.X

Cause

The SQL virtual machines were configured with thin provisioned virtual disks. This configuration incurs a minor performance penalty during the "first write" to any new block, as the storage block must be zeroed out before new data can be written.

Resolution

Change the disk format to thick eager zeroed disk to ensure consistent, optimal I/O performance for write-intensive database operations by pre-allocating and zeroing all blocks at creation.

To change the thick or thin provisioning of a virtual disk, please refer Link: