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UNC path vs. Absolute path to local machine?

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My question is this….

I have a custom app by developers which after completing its calculations, copies about 8GB of data from the local D:\Folder of ‘ServerA’ to the local D:\Folder2 of ‘ServerA’ (same server).

However, the developers used a UNC path for ‘ServerA’ in the config…. //ServerA/D$/Folder copies to //ServerA/D$/Folder2. We find that it takes 13 min. to do this copy.

However, if we change the config file to say copy D:\Folder to D:\Folder2, it takes less than 1 min.

Netstat show hardly any activity on the network during the UNC file copy. What else could be slowing it down 13 fold?!

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Reply To: UNC path vs. Absolute path to local machine?

In reply to UNC path vs. Absolute path to local machine?

With the local disk name, the OS can copy the data directly through the disk controller, without having to engage any extra resources. With the UNC path, it has to go through more steps and a longer path on the motherboard for the data to transfer.

It’s as if your boss told you to move some papers from “the desk on the 9th floor, in the fifth cubicle of the second cubicle-group, of the building in Seattle which is on the street 1st NE at location 2551”, or told you “hand that to the guy in the cube next to yours”. All the time you’d have to spend figuring out which cubicle he meant would be eliminated in the second instruction set. Using “D:” instead of a UNC path is similar.

Reply To: UNC path vs. Absolute path to local machine?

In reply to UNC path vs. Absolute path to local machine?

With the UNC name, your computer will actually query DNS for the ip of itself, unless that info is in the computers cache. Then it probably moves data to the pci bus and then to the disk controller. The extra copy time is because it thinks its moving it across a neteork connection so is probably buffering the sent packets.

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