Commit 13a26d02 authored by ben's avatar ben

Realized FAQ-body, not FAQ.wml should be in cvs


git-svn-id: http://svn.savannah.nongnu.org/svn/rdiff-backup@201 2b77aa54-bcbc-44c9-a7ec-4f6cf2b41109
parent ef3b6917
......@@ -17,6 +17,12 @@ syntax". What's happening?</a></li>
<li><a href="#speed">How fast is rdiff-backup? Can it be run on large
data sets?</a></li>
<li><a href="#statistics">What do the various fields mean in the
session statistics and directory statistics files?</a></li>
<li><a href="#bwlimit">Is there some way to limit rdiff-backup's
bandwidth usage, as in rsync's --bwlimit option?</a></li>
</ol>
<h3>Questions and Answers</h3>
......@@ -223,5 +229,117 @@ locally (about 9GB, 600000 files, maybe 50 MB turnover, 1.1Ghz athlon)
rdiff-backup takes about 35 minutes and is usually CPU bound. Another
user reports an rdiff-backup session takes about 3 hours (80GB, ~1mil
files, 2GB turnover) to back up remotely Tru64 -> linux.
</li>
<p>
<a name="statistics">
<li><strong>What do the various fields mean in the
session statistics and directory statistics files?</strong>
<P>Let's examine an example session statistics file:
<pre>
StartTime 1028200920.44 (Thu Aug 1 04:22:00 2002)
EndTime 1028203082.77 (Thu Aug 1 04:58:02 2002)
ElapsedTime 2162.33 (36 minutes 2.33 seconds)
SourceFiles 494619
SourceFileSize 8535991560 (7.95 GB)
MirrorFiles 493797
MirrorFileSize 8521756994 (7.94 GB)
NewFiles 1053
NewFileSize 23601632 (22.5 MB)
DeletedFiles 231
DeletedFileSize 10346238 (9.87 MB)
ChangedFiles 572
ChangedSourceSize 86207321 (82.2 MB)
ChangedMirrorSize 85228149 (81.3 MB)
IncrementFiles 1857
IncrementFileSize 13799799 (13.2 MB)
TotalDestinationSizeChange 28034365 (26.7 MB)
Errors 0
</pre>
<P>StartTime and EndTime are measured in seconds since the epoch.
ElapsedTime is just EndTime - StartTime, the length of the
rdiff-backup session.
<P>SourceFiles are the number of files found in the source directory,
and SourceFileSize is the total size of those files. MirrorFiles are
the number of files found in the mirror directory (not including the
rdiff-backup-data directory) and MirrorFileSize is the total size of
those files. All sizes are in bytes. If the source directory hasn't
changed since the last backup, MirrorFiles == SourceFiles and
SourceFileSize == MirrorFileSize.
<P>NewFiles and NewFileSize are the total number and size of the files
found in the source directory but not in the mirror directory. They
are new as of the last backup.
<P>DeletedFiles and DeletedFileSize are the total number and size of
the files found in the mirror directory but not the source directory.
They have been deleted since the last backup.
<P>ChangedFiles are the number of files that exist both on the mirror
and on the source directories and have changed since the previous
backup. ChangedSourceSize is their total size on the source
directory, and ChangedMirrorSize is their total size on the mirror
directory.
<P>IncrementFiles is the number of increment files written to the
rdiff-backup-data directory, and IncrementFileSize is their total
size. Generally one increment file will be written for every new,
deleted, and changed file.
<P>TotalDestinationSizeChange is the number of bytes the destination
directory as a whole (mirror portion and rdiff-backup-data directory)
has grown during the given rdiff-backup session. This is usually
close to IncrementFileSize + NewFileSize - DeletedFileSize +
ChangedSourceSize - ChangedMirrorSize, but it also includes the space
taken up by the hardlink_data file to record hard links.
</li>
<a name="bwlimit">
<li><strong>Is there some way to limit rdiff-backup's
bandwidth usage, as in rsync's --bwlimit option?</strong>
<P>There is no internal rdiff-backup option to do this. However, the
--sleep-ratio option can limit overall resource usage, including
bandwidth. Also, external utilities such as <a href="http://www.cons.org/cracauer/cstream.html">cstream</a> can be
used to monitor bandwidth explicitly. trevor@tecnopolis.ca writes:
<pre>
rdiff-backup --remote-schema
'cstream -v 1 -t 10000 | ssh %s '\''rdiff-backup --server'\'' | cstream -t 20000'
'netbak@foo.bar.com::/mnt/backup' localbakdir
(must run from a bsh-type shell, not a csh type)
That would apply a limit in both directions [10000 bytes/sec outgoing,
20000 bytes/sec incoming]. I don't think you'd ever really want to do
this though as really you just want to limit it in one direction.
Also, note how I only -v 1 in one direction. You probably don't want
to output stats for both directions as it will confuse whatever script
you have parsing the output. I guess it wouldn't hurt for manual runs
however.
</pre>
To only limit bandwidth in one directory, simply remove one of the
cstream commands. Two cstream caveats may be worth mentioning:
<ol> <li>Because cstream is limiting the uncompressed data heading
into or out of ssh, if ssh compression is turned on, cstream may be
overly restrictive.</li>
<li>cstream may be "bursty", limiting average bandwidth but allowing
rdiff-backup to exceed it for significant periods.</li>
</ol>
<p>
Another option is to limit bandwidth at a lower (and perhaps more
appropriate) level. Adam Lazur mentions <a
href="http://lartc.org/wondershaper/">The Wonder Shaper</a>.
</li>
</ol>
This diff is collapsed.
......@@ -11,6 +11,7 @@ webprefix = "/home/ben/misc/html/mirror/rdiff-backup/"
if not sys.argv[1:]:
print 'Call with version number, as in "./makeweb 0.3.1"'
print "to move new rpms and tarballs. Now just remaking FAQ and man page."
print
else:
version = sys.argv[1]
RunCommand("cp *%s* %s" % (version, webprefix))
......
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