I am trying to speed test some new LTO tape drives but cannot seem to send data to the tape via dd for any block size above 327,680 bytes. I must have a 1M blocksize for my application.[root@host]# mt -f /dev/nst0 statusBOT ONLINE IM_REP_EN[root@host]# dd if=/dev/zero of=/dev/nst0 bs=327679<this transfers data fine>[root@host]# dd if=/dev/zero of=/dev/nst0 bs=327680<this transfers data fine>[root@host]# dd if=/dev/zero of=/dev/nst0 bs=327681Device or resource busyI have spent many hours trying to debug this. Rebuilt kernels, updated drivers and firmware.REVELATION:The results of running a dmesg shows that there is a bufsize somewhere that is set at the exact critical value that I am seeing my blocksize wall at.[root@host]# dmesg | grep bufsize[    9.114532] st: Version 20160209, fixed bufsize 327680, s/g segs 64Anyone know where I can change this bufsize value?
Anyone know where to change this bufsize value? ( st / mt LTO tape drives )
centos;buffer;tape