This article discusses how you can ensure your Windows Home Server is setup optimally so you can ensure the fastest possible copying speeds.
When you install WHS, it partitions the install hard disk into a 20 Gigabyte primary OS partition and then puts the remaining space as drive D which becomes a 'Primary data partition'.
This 'Primary data partition' is where all of the actual network shares are located, so when you go to \\server\videos your really going to the D drive partition on the primary disk.
When you copy a file across to the videos share for instance, the file is copied onto the D drive partition on your primary home server drive. On the WHS there is a service called the 'Windows Home Server Drive Extender' which is monitoring the videos folder (and all other network shares) which is actually physically located on the D drive 'Primary data partition' of the WHS primary hard disk.
The 'Windows Home Server Drive Extender' looks at the configuration for the share and works out based on this configuration which actual WHS storage drive it will move the file just copied to the share too. The service looks at several thing, such as where other files for the same share are, how much space is free, and if you are using folder duplication.
Once the drive extender service chooses a final destination and moves the media to that destination (If your using duplication it also copies it to another drive for duplication), it creates what is known as a 'tombstone' file in place of the file it just moved to the destination.
The 'tombstone' file is a very small file which points to where the actual file is. This frees up the original space used on the D: drive again and the file is now located on one of the WHS storage drives.
Now this is great as you never need to worry about disk space and you simply see one huge share which can contain the combined space of all of your WHS storage drives.
The problem and the reason copies can be so slow is that if the primary hard disk is slower than the actual WHS storage drives or the drive of the PC which is copying data to it then you're going to get bottlenecked by it.