Exchange 2003 SP2 under Virtual Server 2005 R2

Comments

# Paul Adare said:

Hi John!
As an FYI there is a fairly egregious error in this KB, speficially:
"The network adaptor in the guest operating system will have a maximum bandwidth of 100 megabits. When you size the disk capacity of the virtual machine, the time that is required to perform a full online backup of the Exchange Server data over the network should be considered. Consider adding a dedicated virtual network adaptor for Exchange Server backups."

The NIC in a virtual machine is not constrained to 100 Mb/s as the article states. On a host with Gigabit ethernet it is quite possible that you'll see speeds well in excess of 100 Mb/s. I've been trying for a while now to have someone correct this.

13 December 05 at 9:15 AM

# jhoward said:

Hi Paul! Long time no hear.

...so if we wait a few months, it may get amended :-)

Absolutely right. Common misunderstanding is that it's the emulated adapter is emulated so well that it really does _appear_ in hardware manager and similar tools to be a physical adapter with a speed limitation of 100MBPs in guests. The reality is that (apart from a small virtualisation overhead), it will run at the throughput of the underlying physical host adapter.

However - the article is correct in as much as if are doing heavy-weight network throughput from a VM, it's worth sticking in another host adapter just for that VM's dedicated use. No point starving everything else.

Cheers,
John.

13 December 05 at 9:58 AM

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