When using the wrong block size for the tape devices, you may get the error message Cannot write to device ([87] The Parameter is incorrect.) during the backup or while formatting media. This error may occur if as SAS library, attached to the controller P212-ZM is used. When you try to use a higher block size in Data Protector for such a device you will receive the error above. In this case the only way to use a higher block size is to add RAM to the controller.
Another szenario will be when using 1024K as block size and you update drivers. In a specific case with a QLogic HBA (QMH2462) in the past it was possible to backup data using a block size of 1024K for the devices. The HBA used firmware 5.03.15. After updating Windows drivers to version 9.1.10.27 and firmware to 5.06.05 the customer received the error above. The setting qlfc - tsize 1024 didn’t fix the problem. Qlogic changed the bahavior for the possible block sizes with firmware version 5.04.02. In this particuallar case the customer was required to decrease the block size to 512K and to reformat the media with the new block size within Data Protector. Thanks to Volker for the comment on it.