HI @all,

My question was

“Can I add New Hard Disk with out destroying my current data and OS if so? I had a DL 380 with 5 Harddisks as Raid 5 and one Hot-Spare”? For the extension i wanted to use the Hot-Spare!

Answer
Yes its working,
->select in ACU the Arrays that hold the Hot-Spare, remove them from the sparemanagement by using the sparemanagement button.
->Click on the array that you want to expand and click on expand (select the available drive) click ok!
->Click on the array and click on extend array,now you can see the approx. new size and enter it into the new size box.

Afterwards use diskpart to extend the Volume! Wait until the extension is marked within the controller as complete!

The data will remain!

See reffered links:
http://support.microsoft.com/kb/325590

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=998137

http://forums11.itrc.hp.com/service/forums/questionanswer.do?admit=109447626+1233929228591+28353475&threadId=1301633