Copy-NaHostFile Very Slow on existing VHD's

jasonpadman — Thu, 05 Jun 2025 06:23:55 GMT

Hello Good People,

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.

- Jason

Re: Copy-NaHostFile Very Slow on existing VHD's

CLIFFMILLINER — Tue, 04 Dec 2012 12:58:53 GMT

Hi,

Ive just come across this same problem. Did you eve find out if De-dupe was the cause?

-Cliff

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Copy-NaHostFile Very Slow on existing VHD's

Re: Copy-NaHostFile Very Slow on existing VHD's