Is there any difference?

How setting ArcGIS Server Data Store Folder as local vs. network path will affect the publishing process?

I saw warnings in ArcMap 10.1 when I Analyze the MXD before I publish, complaining that network path is used. (Assuming this might slow down the REST service if network access to MXD data is slow)

Example: My file server has designated shared folder for ArcGIS data called "GisDataStore". It is mapped as local drive on my ArcGIS server, so I can access it both ways:

\MyFileServer\GisDataStore and Z:\GisDataStore

I wonder which I should use to Register the "GisDataStore" folder as ArcGIS 10.2 Server datastore. Local Path Network Path

Here's the warning I am getting:


Medium Unresolved 10027 Layer's data source is referenced via a UNC path

UNC Path Warning

2 Answers 2


Always go with the UNC path (\\server\folder) when creating a data store for ArcGIS Server. This is both cleaner (since you can see the machine name in the path directly) and safer (if there will be a problem with disk mapping, you can have troubles accessing the path).

From Esri Help:

When you use UNC paths to reference your data, all GIS server machines will look to the correct machine for the data. If you store your GIS resources in shared directories, remember that all data source paths within the resource must also use UNC paths or relative paths. For example, if your map document contains layers from three feature classes, the paths to those feature classes must be UNC or relative paths.

A good help page on paths: Paths explained: Absolute, relative, UNC, and URL

You are getting this warning in ArcMap because when using UNC paths network file access is typically slower than direct disk access on your local computer. This can of course negatively affect the map drawing performance since it is as a rule would take longer time to get data over the network comparing to accessing the dataset locally.

Since storing the data on a local disk in your case is not an option, you can ignore this warning or even right-click it and mark as exception to avoid getting it again.

  • UNC path is what I usually use. I guess I should just ignore the ArcMap warning when publishing
    – mitaka
    Jan 28, 2014 at 17:12
  • Would you mind posting an exact warning ArcMap shows when you run Analyze having layers's source data in a registered with UNC data store in the question body? Jan 28, 2014 at 17:28
  • I added it to the question above
    – mitaka
    Jan 28, 2014 at 18:00
  • 1
    One thing to consider, by using the UNC path exclusively versus the ESRI way to have the UNC local but then match the physical on the machine is the network hit. But using UNC to resolve even back to localhost, you are still making a network request that for large apps do mean lost/wasted cycles.
    – D.E.Wright
    Jan 28, 2014 at 18:12
  • @mitaka, edited my answer Jan 28, 2014 at 18:15

It all depends on your geodatabase.

If your gdb is read only, and you dont expect it to get updated often, use local fixed path (i.e. c:\gisdata). Make sure you copy your geodatabase on all GIS servers in your server site at the same exact path. This will save you network latency and can get you good performance through data locaility.

If your gdb is frequently updated, it is in-feasible to duplicate it on multiple GIS servers. Here when UNC shared folder comes in handy. You can use geodatabase replication to update this geodatabase to the shared directory(i.e. \hostname\gisdata). Bear in mind that UNC will slow things down for sure.

One last thing. When using UNC, avoid placing your geodatabase on one of the GIS servers. The reason is if that particular server failed you will lose access to your data even though you might have other gis servers up and running. I suggest using a NAS RAID setup to store your geodatabase. Or better of an enterprise geodatabase.

I have written a humble book about ArcGIS for Server Administration, that include good tips. Chapter 1 and 2 discusses the best practices of using UNC path vs physical paths.

  • It might be a good idea that you disclose that you have written that book yourself; Otherwise it's just undisclosed, self promotion. Feb 5, 2014 at 6:10

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