On Mon, Aug 02, 2010 at 11:38:30AM -0400, Vallon, Justin wrote: > In the svn book, > http://svnbook.red-bean.com/en/1.1/ch05s03.html#svn-ch-5-sect-3.6 on > "Repository Backup" describes some backup methods - hot copy, etc. Given > that enterprise-level filesystems generally support filesystem snapshots, > what is SVN's position on whether such snapshots are sufficient for backups? > > Suppose our criteria is that we unplug the network cable between the writer > (svn commit) and the filesystem. If unplugging the network cable could yield > a repository that is corrupt, then doesn't that mean that there are failure > modes where the repository is corrupted? If a filesystem insures that the > snapshots behave in this way (as if you disconnect the network cable, make an > instant copy, then reconnect), it would seem to imply that these volume-level > snapshots would result in a consistent view. If the snapshots are not > consistent, then atomicity is not being insured (somewhere between > application, client o/s, server o/s, disk controller, media). > > My follow up is whether the svn book could include a word about whether it > blesses (or not) this form of backup?
By chance, this very topic was discussed earlier today. See http://svn.haxx.se/users/archive-2010-08/0019.shtml Quote: "Use 'svnadmin hotcopy' to create a copy of a repository that is consistent from Subversion's point of view. There is no other repository copying tool that can guarantee a consistent repository snapshot." This holds true for filesystem-level snapshots. The atomicity of Subversion's commits only exists from the application's point of view. Stefan
