Hello, I have a master server Win 08 DC running some virtualized 08 STD.I have a HDD for the OS's and and HDD for the data. Microsoft recomends 40GB for the OS; is this still like that in virtualized OS? I have 3 VHD of 40GB but windows installed inside only uses 10GB and 30GB are always free there. If I reduce the size of that VHD, will the performance decreases? Thanks.

festuc said: Microsoft recomends 40GB for the OS; is this still like that in virtualized OS? Yes.Microsoft recommends a 40GB C:\ drive for full Windows Server 2008 installations. Although after initial installation a Windows Server 2008 requires a mere 10GB, more drive space is needed throughout the entire lifecycle of the server, including (but not limited to) an increased page file and hibernation file (due to adding memory), space needed for (Windows) updates, free space needed for (Windows) updates, logs, memory dumpsandthe administrator user profile. All these aspects apply to virtual installations of Windows Server 2008 as well as physical installations. festuc said: If I reduce the size of that VHD, will the performance decreases? No, not immediately.When you supply sufficient disk space to Windows Server 2008 it will perform well. In the course of its lifetime however your Windows Server 2008 installation requires more diskspace. You will encounter problems soon enough. These problems are consistent with problems encountered by many administrators with 4GB C:\ drives in Windows 2000 Server and12GB C:\ drives in Windows Server 2003. (both seemed adequate at the beginning of the lifecycle of the servers)Depending on the workload you willnotice a decrease in performance when you use dynamic disks instead of fixed disks within Hyper-V guests.

Thanks for the reply.Off couse I will use fixed VHD since the performance of the other ones is low.I have make fixed VHD of 20GB do you think it will be not enought for windows to run fine?Best Regards.

I would go for the recommened 40G at least. I have seen too many postings in newsgroups/forums from sysadmins running out of space on the system drive!Bill

Ok, I understand. Thanks.

Just one more question.If I install win2003 will the recomended HDD requirements be less than 40GB? How much will be then?Thanks.

My recommendation for the C:\ drive in Windows Server 2003 and Windows Server 2003 R2 is 24 GB.

Thanks !!!