oystr@maui.cs.washington.edu (Jan Sanislo) (02/05/88)
The problem is not really with rdump. It is with rmt, the "remote" tape facility. Rmt does not make use of the multi-buffer facilities ( nbuf(4) ), while programs such as tar, dd, and dump use n-buffering when dealing with local tapes. If you have the sources, it is fairly easy to modify rmt to use a few (max. 10) 10KB buffers. This will speed up your rdump times by at least a factor of five. Since writes will no longer be synchronous you can run into some problems with error recovery, but overall it is worth the effort. We have been using such a modified rmt for over a year with very good results. One warning: If you don't have Ultrix source and are tempted to hack away on the BSD version, be aware that the Ultrix rmt protocol has some extra operations defined. A careful reading of the Ultrix man page and some minimal extra programming will get you around that.