Back up, or going in reverse?

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This dialog is present in Windows Server Backup 2008 R2.
“the performance of the volume may be reduced by up to 200 percent while it is used to store backups.”

Wait, how slow is that? Let X be the normal performance, and R be the percent reduction, expressed as a decimal number between 0.0 and 1.0. The modified performance (P) can be expressed as: P = X-XR, or in it’s factored form, P = X(1-R).

No reduction in performance (R = 0.0)
P = X(1.0 – 0.0)
P = X

50% reduction in performance (R = 0.5)
P = X(1.0 – 0.5)
P = 0.5X

200% reduction in performance (R = 2.0)
P = X(1.0 – 2.0)
P = X(-1.0)
P = -X

Okay so… while the backup is running, the harddrive is undoing everything I’ve saved? Damn. :(

Anti-virus: the best virus

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I was unboxing and preparing a few new computers this afternoon. One crucial step is joining the computers to our Active Directory domain. Normally this is a painless procedure, but this time I got an error message:

“The following error occurred attempting to join the domain: foo.local: The network path was not found.”

This kind of error message usually means something has gone Very Wrong on the network, so I immediately began analyzing my domain controllers. Everything checked out, so I began a search online and still found nothing. Finally, I inspected the client, and noticed that this machine had Trend Micro anti-virus installed. I opened the properties on the LAN connection and disabled “Trend Micro NDIS 6.0 Filter Driver”, and suddenly it worked perfectly.

Lesson learned: using the default image provided by the OEM is a recipe for disaster. Always start with a clean install.