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<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE refentry PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
<refentry id="vfs_shadow_copy2.8">
<refmeta>
<refentrytitle>vfs_shadow_copy2</refentrytitle>
<manvolnum>8</manvolnum>
<refmiscinfo class="source">Samba</refmiscinfo>
<refmiscinfo class="manual">System Administration tools</refmiscinfo>
<refmiscinfo class="version">&doc.version;</refmiscinfo>
</refmeta>
<refnamediv>
<refname>vfs_shadow_copy2</refname>
<refpurpose>Expose snapshots to Windows clients as shadow copies.
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>vfs objects = shadow_copy2</command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>DESCRIPTION</title>
<para>This VFS module is part of the
<citerefentry><refentrytitle>samba</refentrytitle>
<manvolnum>7</manvolnum></citerefentry> suite.</para>
<para>
The <command>vfs_shadow_copy2</command> VFS module offers a
functionality similar to Microsoft Shadow Copy services.
When set up properly,
this module allows Microsoft Shadow Copy clients to browse
through file system snapshots as "shadow copies" on Samba shares.
</para>
<para>
This is a second implementation of a shadow copy module
which has the following additional features (compared to the original
<citerefentry><refentrytitle>shadow_copy</refentrytitle>
<manvolnum>8</manvolnum></citerefentry> module):
</para>
<orderedlist continuation="restarts" inheritnum="ignore" numeration="arabic">
<listitem><para>
There is no need any more to populate your share's root directory
with symlinks to the snapshots if the file system stores the
snapshots elsewhere.
Instead, you can flexibly configure the module where to look for
the file system snapshots.
This can be very important when you have thousands of
shares, or use [homes].
</para></listitem>
<listitem><para>
Snapshot directories need not be in one fixed central place but
can be located anywhere in the directory tree. This mode helps to
support file systems that offer snapshotting of particular
subtrees, for example the GPFS independent file sets.
</para></listitem>
<listitem><para>
Vanity naming for snapshots: snapshots can be named in any format
compatible with str[fp]time conversions.
</para></listitem>
<listitem><para>
Timestamps can be represented in localtime rather than UTC.
</para></listitem>
<listitem><para>
The inode number of the files can optionally be altered to be
different from the original. This fixes the 'restore' button
in the Windows GUI to work without a sharing violation when
serving from file systems, like GPFS, that return the same
device and inode number for the snapshot file and the original.
</para></listitem>
<listitem><para>
Shadow copy results are by default sorted before being sent to the
client. This is beneficial for filesystems that don't read
directories alphabetically (the default unix). Sort ordering can be
configured and sorting can be turned off completely if the file
system sorts its directory listing.
</para></listitem>
</orderedlist>
<para>This module is stackable.</para>
</refsect1>
<refsect1>
<title>CONFIGURATION</title>
<para><command>vfs_shadow_copy2</command> relies on a filesystem
snapshot implementation. Many common filesystems have native
support for this.
</para>
<para>Filesystem snapshots must be available under
specially named directories in order to be recognized by
<command>vfs_shadow_copy2</command>. These snapshot directory
is typically a direct subdirectory of the share root's mountpoint
but there are other modes that can be configured with the
parameters described in detail below.</para>
<para>The snapshot at a given point in time is expected in a
subdirectory of the snapshot directory where the snapshot's
directory is expected to be a formatted version of the
snapshot time. The default format which can be changed
with the <command>shadow:format</command> option
is @GMT-YYYY.MM.DD-hh.mm.ss, where:
<itemizedlist>
<listitem><para><command>YYYY</command> is the 4 digit year</para></listitem>
<listitem><para><command>MM</command> is the 2 digit month</para></listitem>
<listitem><para><command>DD</command> is the 2 digit day</para></listitem>
<listitem><para><command>hh</command> is the 2 digit hour</para></listitem>
<listitem><para><command>mm</command> is the 2 digit minute</para></listitem>
<listitem><para><command>ss</command> is the 2 digit second.</para></listitem>
</itemizedlist>
</para>
<para>The <command>vfs_shadow_copy2</command> snapshot naming
convention can be produced with the following
<citerefentry><refentrytitle>date</refentrytitle>
<manvolnum>1</manvolnum></citerefentry> command:
<programlisting>
TZ=GMT date +@GMT-%Y.%m.%d-%H.%M.%S
</programlisting></para>
</refsect1>
<refsect1>
<title>OPTIONS</title>
<variablelist>
<varlistentry>
<term>shadow:mountpoint = MOUNTPOINT
</term>
<listitem>
<para>
With this parameter, one can specify the mount point
of the filesystem that contains the share path.
Usually this mount point is automatically detected.
But for some constellations, in particular tests,
it can be convenient to be able to specify it.
</para>
<para>Example: shadow:mountpoint = /path/to/filesystem</para>
<para>Default: shadow:mountpoint = NOT SPECIFIED</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:snapdir = SNAPDIR
</term>
<listitem>
<para>
Path to the directory where the file system of
the share keeps its snapshots.
If an absolute path is specified, it is used as-is.
If a relative path is specified, then it is taken
relative to the mount point of the filesystem of
the share root. (See <command>shadow:mountpoint</command>.)
</para>
<para>
Note that <command>shadow:snapdirseverywhere</command>
depends on this parameter and needs a relative path.
Setting an absolute path disables
<command>shadow:snapdirseverywhere</command>.
</para>
<para>
Note that the <command>shadow:crossmountpoints</command>
option also requires a relative snapdir.
Setting an absolute path disables
<command>shadow:crossmountpoints</command>.
</para>
<para>Example: shadow:snapdir = /some/absolute/path</para>
<para>Default: shadow:snapdir = .snapshots</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:basedir = BASEDIR
</term>
<listitem>
<para>
The basedir option allows one to specify a directory
between the share's mount point and the share root,
relative to which the file system's snapshots are taken.
</para>
<para>
For example, if
<itemizedlist>
<listitem><para>
<command>basedir = mountpoint/rel_basedir</command>
</para></listitem>
<listitem><para>
<command>share_root = basedir/rel_share_root</command>
</para></listitem>
<listitem><para>
<command>snapshot_path = mountpoint/snapdir</command>
</para>
<para>
or
<command>snapshot_path = snapdir</command>
if snapdir is absolute
</para></listitem>
</itemizedlist>
then the snapshot of a
<command>file = mountpoint/rel_basedir/rel_share_root/rel_file</command>
at a time TIME will be found under
<command>snapshot_path/FS_GMT_TOKEN(TIME)/rel_share_root/rel_file</command>,
where FS_GMT_TOKEN(TIME) is the timestamp string belonging
to TIME in the format required by the file system.
(See <command>shadow:format</command>.)
</para>
<para>The default for the basedir is the mount point
of the file system of the share root
(see <command>shadow:mountpoint</command>).
</para>
<para>
Note that the <command>shadow:snapdirseverywhere</command>
and <command>shadow:crossmountpoints</command>
options are incompatible with <command>shadow:basedir</command>
and disable the basedir setting.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:snapsharepath = SNAPSHAREPATH
</term>
<listitem>
<para>
With this parameter, one can specify the path of the share's
root directory in snapshots, relative to the snapshot's
root directory. It is an alternative method to
<command>shadow:basedir</command>, allowing greater control.
</para>
<para>
For example, if within each
snapshot the files of the share have a
<command>path/to/share/</command> prefix, then
<command>shadow:snapsharepath</command> can be
set to <command>path/to/share</command>.
</para>
<para>
With this parameter, it is no longer assumed that a
snapshot represents an image of the original file system or
a portion of it. For example, a system could perform
backups of only files contained in shares, and then
expose the backup files in a logical structure:
</para>
<itemizedlist>
<listitem><para>share1/</para></listitem>
<listitem><para>share2/</para></listitem>
<listitem><para>.../</para></listitem>
</itemizedlist>
<para>
Note that the <command>shadow:snapdirseverywhere</command>
and the <command>shadow:basedir</command> options
are incompatible with <command>shadow:snapsharepath</command>
and disable <command>shadow:snapsharepath</command> setting.
</para>
<para>Example: shadow:snapsharepath = path/to/share</para>
<para>Default: shadow:snapsharepath = NOT SPECIFIED</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:sort = asc/desc
</term>
<listitem>
<para>By default, this module sorts the shadow copy data
alphabetically before sending it to the client.
With this parameter, one can specify the sort order.
Possible known values are desc (descending, the default)
and asc (ascending). If the file system lists directories
alphabetically sorted, one can turn off sorting in this
module by specifying any other value.
</para>
<para>Example: shadow:sort = asc</para>
<para>Example: shadow:sort = none</para>
<para>Default: shadow:sort = desc</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:localtime = yes/no
</term>
<listitem>
<para>This is an optional parameter that indicates whether the
snapshot names are in UTC/GMT or in local time. If it is
disabled then UTC/GMT is expected.
</para>
<para>shadow:localtime = no</para>
</listitem>
</varlistentry>
<varlistentry>
2010-02-09 19:21:01 +03:00
<term>shadow:format = format specification for snapshot names
</term>
<listitem>
<para>This is an optional parameter that specifies the format
specification for the naming of snapshots in the file system.
The format must be compatible with the conversion
specifications recognized by str[fp]time.
</para>
<para>Default: shadow:format = "@GMT-%Y.%m.%d-%H.%M.%S"</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:sscanf = yes/no</term>
<listitem>
<para>
This parameter can be used to specify that the time in
format string is given as an unsigned long integer (%lu)
rather than a time strptime() can parse.
The result must be a unix time_t time.
</para>
<para>Default: shadow:sscanf = no</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:fixinodes = yes/no
</term>
<listitem>
<para>If you enable <command moreinfo="none">shadow:fixinodes
</command> then this module will modify the apparent inode
number of files in the snapshot directories using a hash of the
files path. This is needed for snapshot systems where the
snapshots have the same device:inode number as the original
files (such as happens with GPFS snapshots). If you don't set
this option then the 'restore' button in the shadow copy UI
will fail with a sharing violation.
</para>
<para>Default: shadow:fixinodes = no</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:snapdirseverywhere = yes/no
</term>
<listitem>
<para>
If you enable
<command moreinfo="none">shadow:snapdirseverywhere </command>
then this module will look
out for snapshot directories in the current working directory
and all parent directories, stopping at the mount point
by default.
But see <command>shadow:crossmountpoints</command> how to change
that behaviour.
</para>
<para>
An example where this is needed are independent filesets in
IBM's GPFS, but other filesystems might support snapshotting
only particular subtrees of the filesystem as well.
</para>
<para>
Note that <command>shadow:snapdirseverywhere</command>
depends on <command>shadow:snapdir</command> and needs it to be
a relative path. Setting an absolute snapdir path disables
<command>shadow:snapdirseverywhere</command>.
</para>
<para>
Note that this option is incompatible with the
<command>shadow:basedir</command> option and removes the
<command>shadow:basedir</command> setting by itself.
</para>
<para>Example: shadow:snapdirseverywhere = yes</para>
<para>Default: shadow:snapdirseverywhere = no</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:crossmountpoints = yes/no
</term>
<listitem>
<para>
This option is effective in the case of
<command>shadow:snapdirseverywhere = yes</command>.
Setting this option makes the module not stop at the
first mount point encountered when looking for snapdirs,
but lets it search potentially all through the path
instead.
</para>
<para>
An example where this is needed are independent filesets in
IBM's GPFS, but other filesystems might support snapshotting
only particular subtrees of the filesystem as well.
</para>
<para>
Note that <command>shadow:crossmountpoints</command>
depends on <command>shadow:snapdir</command> and needs it to be
a relative path. Setting an absolute snapdir path disables
<command>shadow:crossmountpoints</command>.
</para>
<para>
Note that this option is incompatible with the
<command>shadow:basedir</command> option and removes the
<command>shadow:basedir</command> setting by itself.
</para>
<para>Example: shadow:crossmountpoints = yes</para>
<para>Default: shadow:crossmountpoints = no</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:snapprefix
</term>
<listitem>
<para>
With growing number of snapshots file-systems need some mechanism
to differentiate one set of snapshots from other, e.g. monthly, weekly,
manual, special events, etc. Therefore these file-systems provide different
ways to tag snapshots, e.g. provide a configurable way to name snapshots,
which is not just based on time. With only <command>shadow:format</command>
it is very difficult to filter these snapshots. With this optional parameter,
one can specify a variable prefix component for names of the snapshot
directories in the file-system. If this parameter is set, together with the
<command>shadow:format</command> and <command>shadow:delimiter</command>
parameters it determines the possible names of snapshot
directories in the file-system. The option only supports Basic
Regular Expression (BRE).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>shadow:delimiter
</term>
<listitem>
<para>
This optional parameter is used as a delimiter between
<command>shadow:snapprefix</command> and <command>shadow:format</command>.
This parameter is used only when <command>shadow:snapprefix</command>
is set.
</para>
<para>Default: shadow:delimiter = "_GMT"</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>EXAMPLES</title>
<para>Add shadow copy support to user home directories:</para>
<programlisting>
<smbconfsection name="[homes]"/>
<smbconfoption name="vfs objects">shadow_copy2</smbconfoption>
<smbconfoption name="shadow:snapdir">/data/snapshots</smbconfoption>
<smbconfoption name="shadow:basedir">/data/home</smbconfoption>
<smbconfoption name="shadow:sort">desc</smbconfoption>
</programlisting>
</refsect1>
<refsect1>
<title>CAVEATS</title>
<para>This is not a backup, archival, or version control solution.
</para>
<para>With Samba or Windows servers,
<command>vfs_shadow_copy2</command> is designed to be an end-user
tool only. It does not replace or enhance your backup and
archival solutions and should in no way be considered as
such. Additionally, if you need version control, implement a
version control system.</para>
</refsect1>
<refsect1>
<title>VERSION</title>
<para>This man page is part of version &doc.version; of the Samba suite.
</para>
</refsect1>
<refsect1>
<title>AUTHOR</title>
<para>The original Samba software and related utilities
were created by Andrew Tridgell. Samba is now developed
by the Samba Team as an Open Source project similar
to the way the Linux kernel is developed.</para>
</refsect1>
</refentry>