Dear Colin,
Sorry for any confusion in my replies. I wasn't referring to a 'common archive', as such, and should have perhaps written it as 'files in common'. Or maybe that's making things worse... Anyway, I think I've got it now - although I admit I remain hazy on exactly how it works - and am reassured that I can, in fact, carry out a full backup over several sessions. Thanks again for your patience and explanations. Regards, John ## On 21-03-2014 21:11, Colin Percival wrote: > On 03/21/14 08:13, John Gamble wrote: > >> Thanks again for your reply. Still slightly confused about this process >> though…. In the scenario I'm thinking about, 'backup-wednesday.part' and >> 'backup-thursday' wouldn't have any common files (or blocks of data). The >> complete archive would be the sum of 'backup-wednesday.part' and >> 'backup-thursday'. > > What "common archive" are you talking about here? If you mean "the archive > you're creating on Thursday", that's the 'backup-thursday' archive I was > talking about, and any blocks from Wednesday which are needed will be included > in that archive automatically. > >> Therefore, how is it possible to delete 'backup-wednesday.part'? Is it, in >> fact, impossible to do so in this case? If so, is there any way to create a >> single complete backup/archive from two or more partial ones, that were >> formed by premature termination of a backup. > > You *can* merge two archives together, but I don't think that's what you want > to > do here. You can just tell tarsnap to create an archive with all of the data > you want it to have, and it will magically pull in bits of previous archives > as > needed. > >> I'm asking all this because given the speed of my upload connection, I know >> that I'll have to stop the initial backup before it completes. Just wanted >> to make sure that I'll ultimately be able to create a complete backup. > > Assuming that you don't have more "new" data each day than you have bandwidth, > yes. Just tell Tarsnap to create a backup with all of your data each day, and > then stop it when you need to. If you have 1 GB/day of bandwidth, you'll end > up with a 1 GB archive on Monday, a 2 GB archive on Tuesday (of which 1 GB was > uploaded new and 1 GB was reused from Monday), a 3 GB archive on Wednesday (of > which 1 GB was uploaded new and 2 GB was reused), etc. until you finally have > a single archive containing all of your data. > >> 1). To terminate an ongoing backup, is the command ^Q? > > Ctrl-Q into the terminal session where you're running tarsnap, or you can send > a SIGQUIT signal (which is what Ctrl-Q translates into). > >> 2). While the backup is ongoing, is it OK to use the computer as normal? > > Of course. UNIX is designed for multitasking. ;-) -- The Wellcome Trust Sanger Institute is operated by Genome Research Limited, a charity registered in England with number 1021457 and a company registered in England with number 2742969, whose registered office is 215 Euston Road, London, NW1 2BE.
