Date: Mon, 12 Jan 1998 19:15:48 -0800 (PST) From: Doug White <dwhite@gdi.uoregon.edu> To: Font <font@Mcs.Net> Cc: questions@FreeBSD.ORG Subject: Re: How best to speed up rdumps? Message-ID: <Pine.BSF.3.96.980112191331.22079V-100000@gdi.uoregon.edu> In-Reply-To: <Pine.BSF.3.95.980106200115.21450B-100000@Mars.mcs.net>
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On Tue, 6 Jan 1998, Font wrote: > I'm dumping across a network to an Exabyte 8505, and while backups on the > FreeBSD 2.2.2+ machine seem to go at 300-600Kbyte/s typically, backups > across the network (from a 2.2.1R machine, so far) seem to only be getting > around 50Kbyte/s. The network is 10baseT with a smattering of 100baseTX, > and is fairly calm at the time of backup. The command I'm using is > > dump 0auf tapeserverbox:/dev/nrst0 filesys > > Should I be specifying a blocksize when doing backups over the network? > If so, how would I go about selecting an ideal blocksize? Would I need to > do several test dumps to determine this? Or should I be looking into > something else for the bottleneck? I bet the tape isn't streaming. In that case, yes, you want to set a blocksize. Try 10 to start with and work from there until you can get the tape drive to stream (that is, not reposition the heads during the backup). We had to use 10 to back up a 486/25 to a Pent/120 box with a Connor 4GB drive. The default blocksize would shoeshine so much it would have taken six months to back up 800 megs :-) Doug White | University of Oregon Internet: dwhite@resnet.uoregon.edu | Residence Networking Assistant http://gladstone.uoregon.edu/~dwhite | Computer Science Major
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