Dear Colin, Thank you for your reply and clarification. If I've understood your example correctly, then:
a). The archive 'backup-thursday' will contain only those files not present in 'backup-wednesday.part' b). If I delete 'backup-wednesday.part', then all the files necessary to create the complete backup (in this case, all the files) will be retained and transferred to 'backup-thursday'. So 'backup-thursday' is now a complete backup. c). To delete 'backup-wednesday.part', the command would be 'tarsnap -d -f backup-wednesday.part'. The reason I'm querying this is that you mention something about having 'delete keys'. Could you clarify this please? I don't see anything about a requirement for that on the Tarsnap general usage page, in the section relating to deleting archives. Thanks again for your advice. Regards, John ## On 19 Mar 2014, at 20:02, Colin Percival <[email protected]> wrote: > Hi all, > > On 03/19/14 07:39, John Gamble wrote: >> Thanks for your reply and apologies for not noticing that bit in the manual. >> So >> if I've understood it properly, the answer is yes, Tarsnap can re-start a >> partial archive. > > Not exactly. You can create a new archive, and any data available on the > server > side -- if you hit ^Q or sent a SIGQUIT and waited for tarsnap to exit > cleanly, > or from automatic checkpoints, or from previous archives -- will be used for > deduplication in order to reduce the amount of new data which needs to be > uploaded. > > But if you were creating an archive named "backup-wednesday" and it was > truncated (deliberately or because it failed and a checkpoint was recovered) > then you'll have an archive named "backup-wednesday.part", and you won't be > able > to create a new archive named "backup-wednesday". You'll be able to create a > new archive named "backup-thursday", however, and then you'll have two > archives > stored. (After which point you might want to delete the first partial > archive.) > >> I guess the command to re-start would be exactly the same as >> the initial command. Would that be a fair assumption? > > Yes except that you need to pick a new name. Once you create an archive with > a > particular name, it cannot be overwritten -- it can only be deleted, and that > only if you have the delete keys. Being able to separate "can create > archives" > and "can delete/destroy previously created archives" (see tarsnap-keymgmt) is > very important in high security environments. > >> If this isn't a completely thick question, how would I know the archive was >> now >> whole and complete? That is, no data missing or lost? > > If tarsnap exits without errors, the archive completed successfully. Also, if > 'tarsnap --list-archives' shows the archive name (without ".part" added to the > end) then the archive was not truncated. > > -- > Colin Percival > Security Officer Emeritus, FreeBSD | The power to serve > Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid > -------------------- John Gamble Senior Computer Biologist Cancer Genome Project Wellcome Trust Sanger Institute Cambridge, UK CB10 1SA Tel: +44 (0)1223 - 834244 Ext: 7703 [email protected] -- 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.
