From 6c1763b5b492f50c43a0dbfe21120d82dcfb7daf Mon Sep 17 00:00:00 2001 From: Joerg Steffens Date: Wed, 23 Dec 2015 12:31:47 +0100 Subject: [PATCH] cleanup FileSet compression description --- manuals/en/main/dirdconf-fileset.tex | 61 ++++++++++++---------------- 1 file changed, 26 insertions(+), 35 deletions(-) diff --git a/manuals/en/main/dirdconf-fileset.tex b/manuals/en/main/dirdconf-fileset.tex index 4125788..82479a1 100644 --- a/manuals/en/main/dirdconf-fileset.tex +++ b/manuals/en/main/dirdconf-fileset.tex @@ -417,26 +417,30 @@ \subsubsection{FileSet Options Ressource} Currently only used for Windows, to exclude files defined in the registry key \registrykey{HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToBackup}, see section \nameref{FilesNotToBackup}. } - \item [compression={\textless}GZIP{\textbar}LZO{\textbar}LZFAST{\textbar}LZ4{\textbar}LZ4HC{\textgreater}] \hfill \\ - \begin{description} - \item [compression=GZIP] \hfill \\ + \item [compression={\textless}GZIP{\textbar}GZIP1{\textbar}...{\textbar}GZIP9{\textbar}LZO{\textbar}LZFAST{\textbar}LZ4{\textbar}LZ4HC{\textgreater}] \hfill \\ \index[dir]{compression} \index[dir]{Directive!compression} + + Configures the software compression to be used by the File Daemon. + The compression is done on a file by file basis. + %If there is a problem reading the tape in a single + %record of a file, it will at most affect that file and none of the other + %files on the tape. + + Software compression gets important if you are writing to a device that does not support compression by itself + (e.g. hard disks). Otherwise, all modern tape drive do support hardware compression. + Software compression can also be helpful to reduce the required network bandwidth, + as compression is done on the File Daemon. + However, using Bareos software compression and device hardware compression together + is not advised, as trying to compress precompressed data is a very CPU-intense task + and probably end up in even larger data. + + You can overwrite this option per Storage resource using the \linkResourceDirective{Dir}{Storage}{Allow Compression} = no option. + + \begin{description} + \item [compression=GZIP] \hfill \\ All files saved will be software compressed using the GNU ZIP - compression format. The compression is done on a file by file basis by - the File daemon. If there is a problem reading the tape in a single - record of a file, it will at most affect that file and none of the other - files on the tape. Normally this option is {\bf not} needed if you have - a modern tape drive as the drive will do its own compression. In fact, - if you specify software compression at the same time you have hardware - compression turned on, your files may actually take more space on the - volume. - - Software compression is very important if you are writing your Volumes - to a file, and it can also be helpful if you have a fast computer but a - slow network, otherwise it is generally better to rely your tape drive's - hardware compression. As noted above, it is not generally a good idea - to do both software and hardware compression. + compression format. Specifying {\bf GZIP} uses the default compression level 6 (i.e. {\bf GZIP} is identical to {\bf GZIP6}). If you want a different compression @@ -448,11 +452,7 @@ \subsubsection{FileSet Options Ressource} compression levels greater than six generally give very little extra compression and are rather CPU intensive. - You can overwrite this option per Storage resource using the \linkResourceDirective{Dir}{Storage}{Allow Compression} option. - \item [compression=LZO] \hfill \\ - \index[dir]{compression} - \index[dir]{Directive!compression} All files saved will be software compressed using the LZO compression format. The compression is done on a file by file basis by the File daemon. Everything else about GZIP is true for LZO. @@ -463,11 +463,7 @@ \subsubsection{FileSet Options Ressource} Note that Bareos only use one compression level LZO1X-1 specified by LZO. - You can overwrite this option per Storage resource using the \linkResourceDirective{Dir}{Storage}{Allow Compression} option. - \item [compression=LZFAST] \hfill \\ - \index[dir]{compression} - \index[dir]{Directive!compression} All files saved will be software compressed using the LZFAST compression format. The compression is done on a file by file basis by the File daemon. Everything else about GZIP is true for LZFAST. @@ -476,11 +472,7 @@ \subsubsection{FileSet Options Ressource} compression ratio than GZIP. If your CPU is fast enough you should be able to compress your data without making the backup duration longer. - You can overwrite this option per Storage resource using the \linkResourceDirective{Dir}{Storage}{Allow Compression} option. - \item [compression=LZ4] \hfill \\ - \index[dir]{compression} - \index[dir]{Directive!compression} All files saved will be software compressed using the LZ4 compression format. The compression is done on a file by file basis by the File daemon. Everything else about GZIP is true for LZ4. @@ -493,13 +485,9 @@ \subsubsection{FileSet Options Ressource} the speed of the LZO compression. So for a restore both LZ4 and LZ4HC are good candidates. - You can overwrite this option per Storage resource using the \linkResourceDirective{Dir}{Storage}{Allow Compression} option. - - \warning{As LZ4 compression is not supported by Bacula, you need to set \linkResourceDirective{Fd}{Client}{Compatible} = no.} + \warning{As LZ4 compression is not supported by Bacula, make sure \linkResourceDirective{Fd}{Client}{Compatible} = no.} \item [compression=LZ4HC] \hfill \\ - \index[dir]{compression} - \index[dir]{Directive!compression} All files saved will be software compressed using the LZ4HC compression format. The compression is done on a file by file basis by the File daemon. Everything else about GZIP is true for LZ4. @@ -512,9 +500,12 @@ \subsubsection{FileSet Options Ressource} the speed of the LZO compression. So for a restore both LZ4 and LZ4HC are good candidates. - You can overwrite this option per Storage resource using the \linkResourceDirective{Dir}{Storage}{Allow Compression} option. + \warning{As LZ4 compression is not supported by Bacula, make sure \linkResourceDirective{Fd}{Client}{Compatible} = no.} + \end{description} + + \item [signature={\textless}SHA1{\textbar}MD5{\textgreater}] \hfill \\ \begin{description} \item [signature=SHA1] \hfill \\