what is stored for the Volume. To change the value for an existing
Volume you must use the {\bf update} command in the Console.
+\item [Action On Purge = \lt{Truncate}]
+\index[dir]{actiononpurge}
+
+This directive \textbf{ActionOnPurge=Truncate} instructs Bacula to truncate
+the volume when it is purged. It is useful to prevent disk based volumes from
+consuming too much space.
+
+\begin{verbatim}
+Pool {
+ Name = Default
+ Action On Purge = Truncate
+ ...
+}
+\end{verbatim}
+
\label{PoolScratchPool}
\item [ScratchPool = \lt{}pool-resource-name\gt{}]
\index[dir]{ScrachPool}
\section{Accurate Fileset Options}
\label{sec:accuratefileset}
-In previous versions, the accurate code used the file creation and
-modification times to determine if a file was modified or not. Now you can specify
-which attributes to use (time, size, checksum, permission, owner, group,
-\dots), similar to the Verify options.
+In previous versions, the accurate code used the file creation and modification
+times to determine if a file was modified or not. Now you can specify which
+attributes to use (time, size, checksum, permission, owner, group, \dots),
+similar to the Verify options.
\begin{verbatim}
FileSet {
for reserving a drive for something special such as a high priority
backup or restore operations.
+\item[Maximum Concurent Jobs = {\it num}]
+\index[sd]{MaximumConcurentJobs}
+
+{\bf Maximum Concurrent Jobs} is a directive that permits setting the maximum
+number of Jobs that can run concurrently on a specified Device. Using this
+directive, it is possible to have different Jobs using multiple drives, because
+when the Maximum Concurrent Jobs limit is reached, the Storage Daemon will
+start new Jobs on any other available compatible drive. This facilitates
+writing to multiple drives with multiple Jobs that all use the same Pool.
+
\item [Maximum Changer Wait = {\it time}]
\index[sd]{Maximum Changer Wait}
\index[sd]{Directive!Maximum Changer Wait}
If you need to specify multiple commands, create a shell script.
+\item[Block Checksum = {\it yes/no}]
+
+ You may turn off the Block Checksum (CRC32) code that Bacula uses when
+ writing blocks to a Volume. Doing so can reduce the Storage daemon CPU usage
+ slightly. It will also permit Bacula to read a Volume that has corrupted
+ data.
+
+ The default is {\bf yes} -- i.e. the checksum is computed on write and
+ checked on read.
+
+ \textbf{We do not recommend to turn this off} particularly on older tape
+ drives or for disk Volumes where doing so may allow corrupted data to go
+ undetected.
+
\item [Minimum block size = {\it size-in-bytes}]
\index[sd]{Minimum block size}
\index[sd]{Directive!Minimum block size}
rewind rewind the tape
scan read() tape block by block to EOT and report
scanblocks Bacula read block by block to EOT and report
+ speed report drive speed
status print tape status
test General test Bacula tape functions
weof write an EOF on the tape
note for labeling tapes, we recommend that you use the {\bf label} command in
the {\bf Console} program since it will never overwrite a valid Bacula tape.
+\subsubsection*{Testing your Tape Drive}
+\label{sec:btapespeed}
+
+To determine the best configuration of your tape drive, you can run the new
+\texttt{speed} command available in the \texttt{btape} program.
+
+This command can have the following arguments:
+\begin{itemize}
+\item[\texttt{file\_size=n}] Specify the Maximum File Size for this test
+ (between 1 and 5GB). This counter is in GB.
+\item[\texttt{nb\_file=n}] Specify the number of file to be written. The amount
+ of data should be greater than your memory ($file\_size*nb\_file$).
+\item[\texttt{skip\_zero}] This flag permits to skip tests with constant
+ data.
+\item[\texttt{skip\_random}] This flag permits to skip tests with random
+ data.
+\item[\texttt{skip\_raw}] This flag permits to skip tests with raw access.
+\item[\texttt{skip\_block}] This flag permits to skip tests with Bacula block
+ access.
+\end{itemize}
+
+\begin{verbatim}
+*speed file_size=3 skip_raw
+btape.c:1078 Test with zero data and bacula block structure.
+btape.c:956 Begin writing 3 files of 3.221 GB with blocks of 129024 bytes.
+++++++++++++++++++++++++++++++++++++++++++
+btape.c:604 Wrote 1 EOF to "Drive-0" (/dev/nst0)
+btape.c:406 Volume bytes=3.221 GB. Write rate = 44.128 MB/s
+...
+btape.c:383 Total Volume bytes=9.664 GB. Total Write rate = 43.531 MB/s
+
+btape.c:1090 Test with random data, should give the minimum throughput.
+btape.c:956 Begin writing 3 files of 3.221 GB with blocks of 129024 bytes.
++++++++++++++++++++++++++++++++++++++++++++
+btape.c:604 Wrote 1 EOF to "Drive-0" (/dev/nst0)
+btape.c:406 Volume bytes=3.221 GB. Write rate = 7.271 MB/s
++++++++++++++++++++++++++++++++++++++++++++
+...
+btape.c:383 Total Volume bytes=9.664 GB. Total Write rate = 7.365 MB/s
+
+\end{verbatim}
+
+When using compression, the random test will give your the minimum throughput
+of your drive . The test using constant string will give you the maximum speed
+of your hardware chain. (cpu, memory, scsi card, cable, drive, tape).
+
+You can change the block size in the Storage Daemon configuration file.
+
\section{Other Programs}
\index[general]{Programs!Other}
\index[general]{Other Programs}
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