Yeah, I reviewed again the guide today and the only difference was the cable... it was connected to the circle connector on top instead of the bottom as illustrated in the guide. The other difference is that I didn't map LUN0 from the VTrak because I'm booting my servers from the internal SAN. I mapped LUN5 to the logical drives on the vtrak.
The problem occurs as soon as I enable the external port on a second server... it's very weird. With only one server connected, performance is good and no issue reading/writing to the vtrak drive.
I'll go tomorrow at our datacenter to change the connector to the bottom one (circle).
EDIT: the IMS we are working with is a MFSYS25v2... don't know if it makes a difference... we have an older MFSYS25 and a second Vtrak where we will test the same thing, just to make sure it's not a device problem.