We have been facing an interesting problem for the last few months with Copy-NaHostFile running very slow for the first time we copy a VHD file if the file has been on the volume for a few days beforehand. We have found that after we do the first Copy-NaHostFile which takes close to 1 hour for a 40gb file, we can then use the new VHD as the source and Copy-NaHostFile is fast again and takes less than a minute to complete.
Let me explain a little more:
If template.vhd has been on the volume for a few days, the below operation is very slow:
Copy-NaHostFile C:\ClusterStorage\Volume1\template.vhd C:\ClusterStorage\Volume1\SysDrive01.vhd(This operation takes 1 hour for a 40GB VHD)
If i then want to make more copies i then use the new VHD i created in the above command as the source and it is fast again:
Copy-NaHostFile C:\ClusterStorage\Volume1\SysDrive01.vhd C:\ClusterStorage\Volume1\SysDrive02.vhd(This operation takes less than 1 minute for a 40GB VHD)
We have de-duplication turned on for the thin CSV Volume / LUN but do not think this should casue Copy-NaHostFile to go very slow but happy to be proven wrong
I will do some more testing with turning off de-duplication and post back here but very interested to hear if anyone else has seen this problem and if you may know what is causing it.