On Friday 02 April 2010 16:38:09 Henrik Johansen wrote: > On 04/ 2/10 01:13 PM, Kern Sibbald wrote: > > 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. > > The average W2K8 System State backup hovers around 11 GB - some of our > servers produce 20+ GB per System State backup.
This is rather mind boggling -- a system state backup that is 20GB compared to a *full* Linux install of well under 4GB. Perhaps if you include all the log files on a busy Linux server, it could amount to the same, but it sure is a lot! Thanks for the information. Kern > > > 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 ------------------------------------------------------------------------------ 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
