When you save a PowerPivot for Excel workbook by using the “Save As” function with Excel, this will use the Office Upload Center as its mechanism to save the file.  This is different than uploading the file by using the SharePoint UI as the SharePoint UI uses a different mechanism via http to upload the file than the Office Upload Center.  The Office Upload Center is included as part of Office 2010 and what is great about this feature is that you can save the file asynchronously.  What this means is that you can save the file and then continue to work with your Excel file in the mean time.  With the SharePoint UI, once you upload the file it is locked and you cannot work with the file until the upload has been completed.  Though, based on current sets of tests, the upload via SharePoint UI is faster than the upload via Office Sync Center so there is the balance between whether you want to work with the file asynchronously or do you want to have faster upload.

To perform an Excel “Save As”, you need only to click on “Save As” within the File option of the Office Ribbon and specify the PowerPivot Gallery of your SharePoint site.

Figure 1: Excel “Save As” functionality

When you do, you’ll notice the Office Upload Center icon pop up in the notification area.

Figure 2: Microsoft Office Upload Center within the Notification area

If you open the Office Upload Center, it will provide a dialog of all of the files that it has pending upload or recently uploaded.

Figure 3: List of files being uploaded (notice Pending Uploads) to the SharePoint site.

When it works great, well, it works great!  In order for the Office Upload Center to perform its tasks, it will create a copy of the file in its cache and then upload the cached version of the file to SharePoint (hence allowing you to work with the original file in the meantime).   Notice how on Figure 4 that there is a large file that is curiously the same size as my original Excel file.

Figure 4: Office Upload Center Cache location

There are times where there are errors with the upload with the Office Upload Center.  If they do, they should show up in the Pending Uploads section of the Office Upload Center.   From here, you click on “Actions” (notice the Actions button in Figure 3) which should allow you to delete it.

If for some reason you cannot delete it, then what you can do is:

1. Kill the Office Upload Center process within task manager (MSOSYNC.exe)
2. Go to the C:\Users\<user>\AppData\Local\Microsoft\Office\14.0 location.  Often if there are issue with uploading through this method, you can delete the files in this directory.You may also want to delete the files in the
   1. C:\Users\<user>\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.MSO
   2. C:\Windows\ServiceProfiles\LocalService\AppData\Local\Temp\TfsStore\Tfs_DAV

Ensure that you have the original files still stored somewhere else before deleting these files but this should clear out the cache and you can then re-start the upload all over again.

For Quick Tips for clearing up space #PowerPivot for SharePoint Uploading, please refer to the linked blog posting.  Note that the reason a PowerPivot for Excel workbook may fail to upload via the SharePoint UI is that you’ll need to clear out the files within SharePoint (as per the blog posting).

Enjoy!