> Message du 20/02/15 11:48 > De : "Bernhard Voelker" > A : [email protected], "Mike Hodson" > Copie à : "didier chavaroche" , "Coreutils" , "Bob Proulx" > Objet : Re: cloning to multiple drives with the "dd" command. > > On 02/20/2015 11:04 AM, Sami Kerola wrote: > > Is there a reason why > > > > $ dd if=/dev/zero count=1 of=/tmp/a of=/tmp/b > > > > could not be made to write to two, or any number of of= destinations, > > in single execution? > > Because we have tee(1) > > dd if=$SOURCE $I_OPTS \ > | tee \ > >( dd $O_OPTS of=$TARGET1 ) \ > >( dd $O_OPTS of=$TARGET2 ) \ > >( dd $O_OPTS of=$TARGET3 ) \ > >( dd $O_OPTS of=$TARGET4 ) > > Getting the errors of the writing dd processes would > be a bit hard though. > > Anyway, this doesn't avoid the IO bottleneck, it just avoids > to read $SOURCE n-times. IMO having more than 3-4 dd's in > parallel is only slowing down the whole process. Maybe the > 'nochache' flag could help to avoid flooding the system cache > at least. > > Have a nice day, > Berny >
Hello everybody. Ok, I recognize trying to clone 23 disks a once can be a little bit hard for my system. It is giving a hard time to the disk cache. But why can't I do it like in 2 or 3 step. cloning 8 drives at once, then another 8 then another 8. I tried this way and cloning the first 8 works fine I have a transfert rate about 100MB/s. But then for the second part, cloning the 8 drives leads to a transfert rate about 20MB/s. I don't understand why the cache is stil so trashed after cloning disks. Is there a way to restore or clean it so I have a Transfert rate about 100MB/s on all my cloning steps? Thanks Regards Didier
