Usually this error can be traced to a discrepancy in block modes. In most instances this error occurs when a tape is made on one machine and is read on a second machine. For example a machine running under SCO 3.2v4.2 creates the archive, then attempting to read the tape on a system running SCO OpenServer 5.

Device Block Mode is the biggest read/write compatibility stumbling block.

SCO 3.2v4.0 will probably default to 512 byte fixed blocks, while OpenServer 5.0.4 will ask the tape drive for its default block mode, which is 0 (variable) for some drives (HP Surestore) and 512 for others, such as Wangtek.

Since "tape setblk" on 3.2v4.0 is broken, the best way to set the tape drives to be compatible is, with a tape in the drive, to issue a "tape -a 512 setblk /dev/xStp0" on the 5.0.4 system.

Reads and writes should then be compatible.