mirror device detached on large file copy

[Chameeya Software Services Ltd.]

Hello running FreeBDs 7.0 on a Celeron 800Mhz and I copied a 1.8G file across from my Windows box to the FreeBSD box. It finished the copy..or during the copy I got the following:kernel : ad6 : FAILURE - device detachedkernel : subdisk6: detachedkernel : ad6 : detachedkernel : GEOM_MIRROR : device dat : provider ad6 disconnected.kernel : g_vfs_done():mirror/dats1d[READ(offset=196937613312, length=16384)]error=6I can only think that perhaps its a time out or a file block error
The file appears okay on ad4 and when I look at it from a NFS mount and through SAMBA on my Windows box.
the configuration is roughly thus
ad2 - boot drive, freeBSD installedad4 - 320G SATAad6 - 320G SATA  - components of mirror dat I used round-robin priority. So I am not sure if the failure is copying the large file from ad6->ad4?
or from ad4->ad6. I presume it is the latter, so would wonder why I got a READ error and not a write.
I put a newfs on ad4 but not ad6 when I was building the mirror. I put the label on ad4 during install (also put newfs during install). Did not put label on on ad6, did not put a newfs on ad6. I Thought the gmirror would take care of that, at any rate it has been working. I have put other files of several hundred megabytes without a problem. But when I tried this 1.8G file this error happened. I have checked the file systems on each device and they appear identical...could be because of the mirror I am reporting only on ad4 and fooling me?
Now I can see some internet documents on this where the newfs should be run on the mirror. Is this the correct procedure
to ensure the file blocks are mapped properly on each drive. The drive, as I have said, has some files on it already and has been working 
fine for a couple of week. It is not a heavily loaded server, its why I am using a slower machine.
I would appreciate any tips on determining why this happened and whether I built the mirror properly.
 
Thanks,
Sal
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