It might be WINSXS directory in Windows 2008 server. Though u didn't mention what service pack u r using now..... In order to reduce the size of Winsxs folder, I am providing and u may try this below:- 1. Uninstall unnecessary applications if possible 2. I am assuming your computer is running Windows Server 2008, please use Cmpcln.exe tool as you mentioned to clean up the space. (It is located under %windir%system32) To do this, please follow these steps: 1. Open an elevated command window (to open an elevated command window: click Start > right-click Command Prompt > and then click Run as administrator.) 2. Type vsp1cln or cmpcln.exe 3. Type Y to start the cleanup process. NOTES: After you use this cleanup tool, you will no longer be able to remove the Service Pack, should any problems occur. Make sure that the system is stable before using. This tool is a one-time use tool. Once it's used it will no longer work on the same installation. 4. Delete blobs.bin file and reboot the system. NOTES: The blobs.bin file which is located at WindowswinsxsManifestCacheblobs.bin is used as a caching mechanism for servicing operations that are set to happen against the system. The file will naturally grow and shrink in size as various servicing actions take place against the machine and are satisfied. It the file grows out of control, let’s say it occupies several GBs space. You can safely delete this file without any fear of it damaging anything on the server as this file is just for caching. The file will be recreated when you reboot the system. The Last Words : If deleting the file doesn't resolve the growth issue, set the permission of the file to deny everyone from writing to it. The stack will see a failure to write to this as a signal that it doesn’t need caching and it will move on servicing files. Good Luck !

It might be WINSXS directory in Windows 2008 server. Though u didn't mention what service pack u r using now..... In order to reduce the size of Winsxs folder, I am providing and u may try this below:- 1. Uninstall unnecessary applications if possible 2. I am assuming your computer is running Windows Server 2008, please use Cmpcln.exe tool as you mentioned to clean up the space. (It is located under %windir%system32) To do this, please follow these steps: 1. Open an elevated command window (to open an elevated command window: click Start > right-click Command Prompt > and then click Run as administrator.) 2. Type vsp1cln or cmpcln.exe 3. Type Y to start the cleanup process. NOTES: After you use this cleanup tool, you will no longer be able to remove the Service Pack, should any problems occur. Make sure that the system is stable before using. This tool is a one-time use tool. Once it's used it will no longer work on the same installation. 4. Delete blobs.bin file and reboot the system. NOTES: The blobs.bin file which is located at WindowswinsxsManifestCacheblobs.bin is used as a caching mechanism for servicing operations that are set to happen against the system. The file will naturally grow and shrink in size as various servicing actions take place against the machine and are satisfied. It the file grows out of control, let’s say it occupies several GBs space. You can safely delete this file without any fear of it damaging anything on the server as this file is just for caching. The file will be recreated when you reboot the system. The Last Words : If deleting the file doesn't resolve the growth issue, set the permission of the file to deny everyone from writing to it. The stack will see a failure to write to this as a signal that it doesn’t need caching and it will move on servicing files. Good Luck !