What is the NAS device?
Does it use a VMWARE add-on for management of the device?
Iomega NAS. Compatible for Vmware, but i had not install any add-on. My DC named server is also veeam server, no problem for 2 years until now. NAS is connected to host with iscsi.
Q: "When replication begins, DC_Replica's harddisk added to DC, And when backup finishes, disk deleted. Is this normal ?"
A: Yes, it's normal. Veeam automatically selects the best possible mode for transferring information. Here's an example of "hotadd" mode.
Q: "But two days ago one machine backup give this error: connection was forcibly closed by a remote host"
A: This is a bit difficult to troubleshoot error. Could be a problem with the network or some timeout. Good tactic is to update Veeam to the latest version and read following thread for considerations: https://forums.veeam.com/veeam-backup-replication-f2/an-existing-connection-was-forcibly-closed-by-the-remote-hos-t20123…