well :-)
Parity checking is one part of the SCSI standard that is used to assure that the datas read (or written) are really what is on the scsi device.if I remember well, setting that jumper will invalidate the parity checking.
You should let that jumper in the state it was. :-)
Important Note :
SCSI ID 7 is reserved to the SCSI controler (here the Squirrel interface) and should never be used for a drive!
This is valid for all SCSI controlers and devices.
