Have any of you had experience working with (rather) large virtualized networks?
It's been suggested that I virtualize my network. To me the advantages are not clear but the risks are. Since I am old-school and highly risk-averse when it comes to computer technology, I need to hear different perspectives from people who are not trying to sell me anything.
We have 7 servers that are candidates for virtualization on a single hypervisor.
- Domain controller (currently Linux but may be replaced with Windows) - Heavily used Linux file server that includes two VFP databases and serves up a large and growing number of network shares on which many users depend heavily - Lightly used Windows Medicaid billing server running software that is very slow and requires maximum throughput/speed - Lightly used Windows Accounting server that is running software that is very slow and requires maximum throughput/speed - Windows RDP server that has about 15 authorized users; there's slow growth on this, and it runs separate instances of my VFP application for some of those users. - Windows Document management server - Windows 7 Ultimate 64-bit Antivirus server (not a Windows server OS)
The Accounting and Medicaid boxes both have SQL Server Express databases, and there is client software on the workstations that access it, but the servers also have additional software installed as well. So it does not appear to me that this is either fully fat client-thin server or fully server-hosted software.
The network has about 130 workstations, connected through four gigabit switches, and there is moderate growth on that. We have a 25 Mbps synchronous internet connection and it is heavily used by many workstations. There are only a couple of network printers; most people have desktop printers.
There is a VoIP phone server on a separate physical network but which is connected to the computer network for remote-access purposes and to enable use of "switchboard" software on a few workstations.
There are two other servers on the network that are not candidates for virtualization:
- Fax server; has legacy dedicated hardware - Backup server, which is almost constantly either running scripts to backup and transfer data from the other servers, to itself and to a removable drive, or having data fed to it from other servers.
Total "live" data on the network servers is about 1 TB; we can expect slow-to-moderate growth on that.
The risks it seems to me are:
1. Fail-over: If the hypervisor goes down, nobody, but nobody, can do any work. Therefore I need a redundant mirrored system on a separate box, and a robust mechanism to continuously mirror the data without affecting performance. Is that really possible?
2. What is going to be the real, day-to-day effect of using a virtualized RDP server in a stack of other virtualized servers, some of which have heavy intranet traffic? I do not want to be in a situation where I'm told there are no worries and then, this system is installed, and the thing is dog-slow.
3. In fact, I don't want that to happen in relation to any of the applications we are using. What is a realistic expectation on this?
If the reality is that I will be assuming greater risks than I face now with separate physical servers, and those risks cannot be mitigated effectively, then are there any countervailing advantages to virtualization that would be great enough to justify making this change?
Thanks to all for the benefit of your experience.
Ken Dibble www.stic-cil.org