Hi Emmanuel, > Hmm in fact if we keep using MB we'll be stuck when tapes reach ~2 PB > which leaves some time to think about it, until LTO-15 circa 2036 :) There will be other issues to solve before then (by LTO-9 2 with compression or LTO-10 without compression and we're at LTO-7 now). Take tar format archives with a standard block size of 10k can take this much data to get to 2^32 blocks and cause the current 32bit block number to wrap: 43,980,465,111,040 (2^32 * 10240) After that much data has been written the SCSI-2 command READ POSITION will not be able to show the current position correctly (which is what the st driver uses to determine the position for an MTIOCPOS). It may be less than that since some drives include file marks in the logical block number if the program that produced the tape writes them out. That means switching to the extended block id form of READ POSITION so we have 64bit counts for those values, see page 150: https://docs.oracle.com/cd/E21419_04/en/LTO5_Vol3_E5b/LTO5_Vol3_E5b.pdf That's going to require new ioctls like MTIOCPOS64 and other changes within the driver to support larger types for holding some values. That will also raise all sorts of fun compatibility questions as well (should MTIOCPOS work at all for such a tape drive or should it work until something overflows and return what data it can and give an errno of -EOVERFLOW etc). That's probably the correct time to also look at adding support for more partitions. Not sure when the extended block id form of READ POSITION got added but it may mean only supporting the wider values only with tape drives that support REPORT SUPPORTED OPCODES (if that can indicate that it supports READ POSITION with extended block ids and anything else required to support block numbers larger than 2^32). The 0x91 version of SPACE needs to be used as well (the 32bit version 0x11 Is currently used) to allow tape movement with counts >2^32. That requires a new ioctl call. I haven't looked at what else may need to change but there's likely to be more. The alternate version of SPACE is from page 220 of the above HP LTO5 tape reference. Thanks Shane P.S. you could force the above changes now using a 512 byte block size since the block number would wrap at this size on LTO (ignoring the fact that it wouldn't make sense to use a block size that small on LTO): 2,199,023,255,552 (2^32*512) ��.n��������+%������w��{.n�����{������ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
