Issue : 
VirtualMachine.MountToolsInstaller" for object " on vCenter Server . vix error code = 21011


cause : 
The problem occur while VM is not able to map the VMware tools from the ESXi server. 

Solution :
1. Open ESXi -- COnfiguration -- Security Profile -- Click on SSH -- Option -- Start the SSH service

2. Open Winscp and connect with the ESXi server

3. Go to vmfs/volumes/5371................./packages/5.5.0/VMtools

4. Download Windows.iso to any datastore which is connected with the esxi server.

5. Go to VM Console and map the windows.iso image in the CD ROM

6. Install /  upgrade the VMware Tools

7. Restrat the machine

8. Go back to ESXi  --- COnfiguration -- Security Profile --choose SSH  -- Stop the service.



Now, Problem is solved.