Jens / Jeff, Each libata driver registers a .dma_boundary field with SCSI. This field is used to prevent merging of bio segments across a hardware limitation boundary, usually 0xffff. This looks like it works for regular block I/O, but I'm not so sure about SGIO originated requests. Any thoughts, or code you can point me to? Thanks Mark - : send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html