D. Allen [CGL]) (09/19/89)
Consider a vs3100 and a vs3200 on an Ethernet, both running Ultrix 3.0, soon to be Ultrix 3.1 (UWS 2.1). The vs3200 has the TK70 tape drive. I tried the following to back up 119 Mb from an rz55 on the vs3100 to the TK70 on the vs3200: vs3100# rdump 0f vs3200:/dev/rmt0h /dev/rrz1c - estimated 8 HOURS to write 119 Mb to the TK70 vs3100# dump 0f - /dev/rrz1c | rsh vs3200 exec dd bs=20k of=/dev/rmt0h - estimated 22 MINUTES to write 119 Mb to the TK70 Surely there must be a way to get rdump to do better than 8 HOURS for 100 Mb? Enlighten me. I would have thought rdump and rmt would be able to pick the fastest way without my help; I must be very wrong. -- -IAN! (Ian! D. Allen) idallen@watcgl.uwaterloo.ca idallen@watcgl.waterloo.edu 129.97.128.64 Computer Graphics Lab/University of Waterloo/Ontario/Canada
envbvs@epb2.lbl.gov (Brian V. Smith) (09/20/89)
In article <11523@watcgl.waterloo.edu>, idallen@watcgl.waterloo.edu (Ian! D. Allen [CGL]) writes: < Consider a vs3100 and a vs3200 on an Ethernet, both running Ultrix 3.0, < soon to be Ultrix 3.1 (UWS 2.1). The vs3200 has the TK70 tape drive. I < tried the following to back up 119 Mb from an rz55 on the vs3100 to the < TK70 on the vs3200: < < vs3100# rdump 0f vs3200:/dev/rmt0h /dev/rrz1c < < - estimated 8 HOURS to write 119 Mb to the TK70 < < vs3100# dump 0f - /dev/rrz1c | rsh vs3200 exec dd bs=20k of=/dev/rmt0h < < - estimated 22 MINUTES to write 119 Mb to the TK70 < < Surely there must be a way to get rdump to do better than 8 HOURS for < 100 Mb? Enlighten me. I would have thought rdump and rmt would be < able to pick the fastest way without my help; I must be very wrong. The problem is that rdump doesn't use multiple buffer write to the tape, so the TK50/70 doesn't have a chance at streaming. dd and tar do use the multiple buffer scheme, so until DEC changes rdump to do this I would never consider using it. _____________________________________ Brian V. Smith (bvsmith@lbl.gov) Lawrence Berkeley Laboratory I don't speak for LBL, these non-opinions are all mine.