Date: Wed, 8 Oct 2008 13:20:02 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-hackers@FreeBSD.ORG, "Zaphod Beeblebrox" <zbeeble@gmail.com>, Volker <volker@vwsoft.com>, Evren Yurtesen <yurtesen@ispro.net> Subject: Re: continuous backup solution for FreeBSD Message-ID: <200810081120.m98BK2fV043545@lurza.secnetix.de> In-Reply-To: <86iqs3sdtp.fsf@ds4.des.no>
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Dag-Erling Smørgrav wrote: > "Zaphod Beeblebrox" <zbeeble@gmail.com> writes: > > "Dag-Erling Smørgrav" <des@des.no> writes: > > > What really annoys me with this thread is that nobody has provided > > > any information at all that would allow someone to understand what > > > needs to be done and estimate how hard it would be. > > Well... I hinted that a hammer port would be sufficient (although they > > need to finish their replication design) and I hinted that the hammer > > approach may be graftable to ZFS. Both reasonably large effort-wise > > (but probably within the scope of a single developer with sufficient > > time). > > No... you're so far off the mark it's not even funny, especially when > it's been repeatedly pointed out to you. This is not a file system, > it's a backup system. It's not designed to survive a disk crash or an > accidental file deletion, it's designed to survive a direct missile > strike on your colo center. > > To quote Wikipedia, "CDP is a service that captures changes to data to a > separate storage location" - emphasis on "separate". FWIW, the HAMMER file system _does_ support replication to remote targets (thus "separate"). Unfortunately they call this feature "mirroring", which is misleading at best. It's really rather a replication mechanism, much like the binlog of MySQL. It can be used for various purposes, including live mirroring, delayed mirroring, archiving, backup and point-in-time recovery. Well, of course, all of that doesn't help us at all because HAMMER doesn't exist on FreeBSD. However, ZFS does exist on FreeBSD, and I think it wouldn't be impossible to add similar features to ZFS. Another possibility would be to extend gjournal by adding time stamps to journal transactions and a possibility to feed the journal to a pipe, socket or whatever. And of course a client-side implementation that does something useful with the journal stream. This might even be a good SoC project. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "File names are infinite in length, where infinity is set to 255 characters." -- Peter Collinson, "The Unix File System"
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