[svandamme]

don't mix match different scsi disks within the same stripe set
the raid 5 will be bottlenecked by it's slowest disk

i would also hesitate to slap it on the same scsi channel, because it will eat away bandwith from the raid5

if all you want to do , is migrate the data to the Raid volume
i'de either connect it to a second simple scsci controller, or even better, copy it over the network from another pc

i've done data recovery and migrations and what not from back in the days with compaq IDA raid, till these days with Fiber channel SAN's and what not.. and it's been my MO ,

to A
not eff around with the redundant, fault tolerant hardware, by not plugging in disks that don't belong there, leave the raid machine as is...

and B
not eff around with the hardware holding the data that has to be recovered, by plugging it in to raid controllers that often have automated logic that goes "hey ,new disk, initialize now"

which can happen if "somebody" configured the raid to consider a free slot as an online spare, and Murphy's law kicks in , and kills a live disk , just 2 minutes after you just plugged in the data disk ...

data to be recovered : freshly installed machine, with Antivirus and correct drivers, dedicated controller for the disk that has to be recovered, and then duplicate the data as fast as possible before doing anything else

i've never lost data... ever...
i've seen lot's of others loose data...