On 22.05.2009 20:30, Ming Zhang wrote: > it become a BDD question now.. ;) > > On Fri, May 22, 2009 at 5:37 PM, Matthias Schniedermeyer <m...@citd.de> wrote: > > On 22.05.2009 16:25, Ming Zhang wrote: > >> Hi All > >> > >> We want to use rsync to backup a live Berkley db to a remote site. BDB > >> has a requirement that read has to be in the unit of db page size. So > >> wonder how could we make sure that rsync can follow that? If we need > >> to change the code, where we should begin to look at? Thanks! > > > > The read block size is irrelevant, the problem you have is consistency. > > > > If you want a working copy of a database (and this goes for any > > database) you have to quiescent the database first. Otherwise the > > file(s) in the filesystem may not be in a consistent state. > > if i stop the DB operation, then yes, block size does not matter any more.
Except doing the database copy on a higher level there is not much else you can do. > but actually base on BDB document, you CAN copy the files, just need > to be careful on the order of files that get copied. i will use > db_hotbackup to figure out the file order and feed that to rsync as > files-from. now the block size question become relevant. No. The block size is NEVER relevant for a copy via rsync, bits are bits regardless of you copying them bit by bit or in larger groups. The man-page of db_hotbackup meantions (indirectly) that the backup is without cooperation from the application and the database content may be inconsistent. Not from the technical standpoint of BDB, but from the high-level application standpoint. The application has to use transactions correctly so that the database-content is consistent at any point in time. In short: If your application does correcy transactions, hotbackup appears to be a useable variant of the "snapshot"-db-backup type. > > Also you must either quiescent the database the WHOLE TIME you back it > > up, or you must use some form of snapshoting for the filesystem and then > > backup the snapshot. (quiescent -> Snapshot -> unquiescent) > > (Or use some other database depend backup procedure) > > > > How you quiescent a database is about as database dependend as it can > > get and personally i don't know how the procedure is for a BDB. > > But i guess(!) you need cooperation from the program(s) working with the > > db. > > > > > > > > Googling: backup berkeley db > > Appear to give answers, but i only took a quick glance. > > > > > > > > Bis denn > > > > -- > > Real Programmers consider "what you see is what you get" to be just as > > bad a concept in Text Editors as it is in women. No, the Real Programmer > > wants a "you asked for it, you got it" text editor -- complicated, > > cryptic, powerful, unforgiving, dangerous. > > > > -- Bis denn -- Real Programmers consider "what you see is what you get" to be just as bad a concept in Text Editors as it is in women. No, the Real Programmer wants a "you asked for it, you got it" text editor -- complicated, cryptic, powerful, unforgiving, dangerous. -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
