<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <!--Converted with LaTeX2HTML 2008 (1.71) original version by: Nikos Drakos, CBLU, University of Leeds * revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan * with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --> <HTML> <HEAD> <TITLE>Overall Format</TITLE> <META NAME="description" CONTENT="Overall Format"> <META NAME="keywords" CONTENT="developers"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <META NAME="Generator" CONTENT="LaTeX2HTML v2008"> <META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"> <LINK REL="STYLESHEET" HREF="developers.css"> <LINK REL="next" HREF="Serialization.html"> <LINK REL="previous" HREF="Storage_Daemon_File_Output.html"> <LINK REL="up" HREF="Storage_Media_Output_Format.html"> <LINK REL="next" HREF="Serialization.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html1107" HREF="Serialization.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html1101" HREF="Storage_Media_Output_Format.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html1095" HREF="Storage_Daemon_File_Output.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html1103" HREF="Contents.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html1105" HREF="GNU_Free_Documentation_Lice.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html1108" HREF="Serialization.html">Serialization</A> <B> Up:</B> <A NAME="tex2html1102" HREF="Storage_Media_Output_Format.html">Storage Media Output Format</A> <B> Previous:</B> <A NAME="tex2html1096" HREF="Storage_Daemon_File_Output.html">Storage Daemon File Output</A> <B> <A NAME="tex2html1104" HREF="Contents.html">Contents</A></B> <B> <A NAME="tex2html1106" HREF="GNU_Free_Documentation_Lice.html">Index</A></B> <BR> <BR> <!--End of Navigation Panel--> <H1><A NAME="SECTION001140000000000000000"></A> <A NAME="3906"></A> <A NAME="3907"></A> <BR> Overall Format </H1> <P> A Bacula output file consists of Blocks of data. Each block contains a block header followed by records. Each record consists of a record header followed by the record data. The first record on a tape will always be the Volume Label Record. <P> No Record Header will be split across Bacula blocks. However, Record Data may be split across any number of Bacula blocks. Obviously this will not be the case for the Volume Label which will always be smaller than the Bacula Block size. <P> To simplify reading tapes, the Start of Session (SOS) and End of Session (EOS) records are never split across blocks. If this is about to happen, Bacula will write a short block before writing the session record (actually, the SOS record should always be the first record in a block, excepting perhaps the Volume label). <P> Due to hardware limitations, the last block written to the tape may not be fully written. If your drive permits backspace record, Bacula will backup over the last record written on the tape, re-read it and verify that it was correctly written. <P> When a new tape is mounted Bacula will write the full contents of the partially written block to the new tape ensuring that there is no loss of data. When reading a tape, Bacula will discard any block that is not totally written, thus ensuring that there is no duplication of data. In addition, since Bacula blocks are sequentially numbered within a Job, it is easy to ensure that no block is missing or duplicated. <P> <HR> <!--Navigation Panel--> <A NAME="tex2html1107" HREF="Serialization.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html1101" HREF="Storage_Media_Output_Format.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html1095" HREF="Storage_Daemon_File_Output.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html1103" HREF="Contents.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html1105" HREF="GNU_Free_Documentation_Lice.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html1108" HREF="Serialization.html">Serialization</A> <B> Up:</B> <A NAME="tex2html1102" HREF="Storage_Media_Output_Format.html">Storage Media Output Format</A> <B> Previous:</B> <A NAME="tex2html1096" HREF="Storage_Daemon_File_Output.html">Storage Daemon File Output</A> <B> <A NAME="tex2html1104" HREF="Contents.html">Contents</A></B> <B> <A NAME="tex2html1106" HREF="GNU_Free_Documentation_Lice.html">Index</A></B> <!--End of Navigation Panel--> <ADDRESS> 2012-01-24 </ADDRESS> </BODY> </HTML>
