Date: Tue, 13 Jan 1998 23:14:25 -0600 (CST) From: Font <font@Mcs.Net> To: Doug White <dwhite@resnet.uoregon.edu> Cc: questions@FreeBSD.ORG Subject: Re: How best to speed up rdumps? Message-ID: <Pine.BSF.3.95.980113230911.15613A-100000@Jupiter.Mcs.Net> In-Reply-To: <Pine.BSF.3.96.980112191331.22079V-100000@gdi.uoregon.edu>
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I did do some trials from a P100 IDE box to a PPro200 AHA2940UW box, both
since upgraded a bit to 2.2.5R, and on the same small test partition got:
-b 10 ~50K/s
-b 16 ~50K/s
-b 24 ~80K/s
-b 32 ~220K/s
-b 48 ~220K/s
-b 60 ~220K/s
The command used was
dump 0au -b # -f remotehost:/dev/nrst0 /mountpoint
So now I'm using -b 32 and I've seen dump rates of up to 400K/s on other
dumps, which is acceptable. Thanks for the tips, they helped encourage me
to experiment and learn. :-)
dw
A bug in my MUA causes news.announce.newusers font
to be sent to beneficiaries and senders of UCE/SPAM. @
mcs.net
Wishes are like dishes.
On Mon, 12 Jan 1998, Doug White wrote:
> Date: Mon, 12 Jan 1998 19:15:48 -0800 (PST)
> From: Doug White <dwhite@gdi.uoregon.edu>
> Reply-To: Doug White <dwhite@resnet.uoregon.edu>
> To: Font <font@Mcs.Net>
> Cc: questions@FreeBSD.ORG
> Subject: Re: How best to speed up rdumps?
>
> 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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