scott@prism.gatech.EDU (Scott Holt) (02/28/91)
We have a number of IBM 8mm drives, both internal an external, connected to various RS 6000 systems. I have come across a problem using backup with the devices. In particular, if the block size device attribue is set to 0 (indicating a variable length block), tapes subsequently written with backup cannot be read. I have poured through various manuals and found no mention of the range of legal block sizes for the 8mm devices. The system does not issue any kind of message when the block size attribute is set to zero. To confuse things even more, other commands (such as tar and dd) access the drive fine with the blocksize set to 0, only backup/restore seem to dislike it. So, the query is 1) Is backup broke? 2) Is setting blocksize to zero on the 8mm device a dumb idea? If so, why does the system let you do it? 3) Where might the legal attribute values for particular devices be documented? - Scott
karish@mindcraft.com (Chuck Karish) (03/02/91)
In article <22985@hydra.gatech.EDU> scott@prism.gatech.EDU (Scott Holt) writes: >We have a number of IBM 8mm drives, both internal an external, >connected to various RS 6000 systems. I have come across a >problem using backup with the devices. In particular, if the >block size device attribue is set to 0 (indicating a variable >length block), tapes subsequently written with backup cannot be >read. > >So, the query is > >1) Is backup broke? Probably. >2) Is setting blocksize to zero on the 8mm device a dumb idea? It's impractical on the 8mm and 1/4" drives. It's necessary, though, on the 9348 9-track drive; that one won't support tar or cpio unless the blocksize is set to zero. >3) Where might the legal attribute values for particular devices > be documented? I don't know where they're documented, but the block sizes that work are 512 and 1024. There seems to have been a change between 3002 and 3003. I wish IBM would provide a utility that knows how to make tape drives work efficiently to be used as a filter between other utilities and the drives, instead of building different partial knowledge of the drives into different utilities. Chuck Karish karish@mindcraft.com Mindcraft, Inc. (415) 323-9000