Hello, Over the past several weeks James and I have been discussing a rather sticky point with doing System State backup and restores via a Bacula plugin.
The basic problem works down to the fact that we do the backup, we first have the names of the files to backup, which we do, then we get some special writer XML data to save. This is no problem. However, on the restore, to properly restore to writers, we must first present the XML data, then we can write the file data. This is a real problem because Bacula puts data sequentially on a Volume (tape or disk) and then restores it sequently. There is no mechanism in Bacula to write some data after backing up files, then get that data *before* restoring the files. For a typical system state backup, this XML metadata represents something like the following in bytes: 2604 463820 754 3378 1610 4636 1414 there are a number of meta data files, because the system state backup consists of backing a number of different "components" Now, we could compress this data, and store it in the catalog, but that is a bit "ugly" and requires transmitting it back to the FD in some way during a restore. Compressing the data reduces it to about 20-30KB rather then the 500KB. Another idea is to spool the file data in either the File daemon or Storage daemon, until we receive and write the meta data to the Volume, and then despool the file data -- thus during a restore the xml meta data would be restored (given to the plugin) first. On James' system the file data backed up during s systems state is about 200MB (not a lot to spool). However, he believes that he has seen something like 1GB of data produced by ntbackup, so that would be a lot more data to spool. One of the problems of spooling, is that if it fails, it will be relatively serious, because in order to get the meta data, we need to tell VSS that the backup of the files was complete, which changes the state of VSS (i.e. if you are doing an incremental backup of the system log files, you cannot just repeat the operation). Does anyone have any ideas or suggestions preferences? Best regards, Kern ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Bacula-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/bacula-devel
