pjb@tcom.stc.co.uk (Peter J. Bishop) (01/31/89)
Reply-to: pjb@tcom.stc.co.uk (Peter J. Bishop) At this site we have 2 Sun S/320 and 3 DEC Microvax Q5's. On one of the Suns and one of the DECs we have 6250 bpi tape drives. For this reason our main backups are performed using 'rdump'. Unfortunately this seems to run DEADLY SLOW. This makes our backups last approx 35 hours. As you can guess, this is impractical. My questions are, a) Does anyone know why rdump is so slow (the machines are connected by ethernet. b) How can I speed it up or, c) Are there any alternatives. Thanks in advance of your assistance, (and sorry if this is the wrong newsgroup to send this to). -- Cheers, Peter Bishop. <pjb@tcom.stc.co.uk> || ...!mcvax!ukc!stc!pjb STC TNDD, Harlow Technical Centre, 20-22 Edinburgh Way, Harlow. Essex Phone : +44 279 626626 x2795
richard@vajra.UUCP (Richard Wood) (02/04/89)
Reply-to: richard@vajra.UUCP (Richard Wood) In article <81522@felix.UUCP> pjb@tcom.stc.co.uk (Peter J. Bishop) writes: > > On one of the Suns and one of the DECs we have 6250 bpi tape drives. > For this reason our main backups are performed using 'rdump'. > Unfortunately this seems to run DEADLY SLOW. This makes our backups > last approx 35 hours. As you can guess, his is impractical. > >My questions are, > > a) Does anyone know why rdump is so slow (the machines are connected > by ethernet. > > b) How can I speed it up or, > > c) Are there any alternatives. I suspect that the server rmt process isn't implemented with N-buffer IO, and thus isn't keeping the tape in streaming mode. A streaming tape in start-stop mode is a painful sight to behold. Suggestion: Try dump 0unf - /PARTITION | rsh dd of=/dev/rmt0h (add other parameters as required) In other words, just pipe the data across the net manually. The "dd" should be able to keep the tape in streaming mode. (Actually, we were trying to get rmt to do streaming in v3.0 - I don't know if it made it. Which version of each OS are you using?) -- ---------------------------------------------------------------------------- Does it need saying that I'm not speaking as an official representative of DEC? =============================================================================== Richard Wood ! U. S. Worksystems, Palo Alto ! Digital Equipment Corporation