Commit 495beb42 authored by Manuel Franceschini's avatar Manuel Franceschini
Browse files

Add file-based options to gnt-instance man-page

Reviewed-by: iustinp
parent 742f39ac
......@@ -82,8 +82,15 @@
<arg><replaceable>initrd_path</replaceable></arg>
</group> </arg>
<sbr>
<arg>--file-storage-dir <replaceable>dir_path</replaceable></arg>
<arg>--file-driver <group choice="req">
<arg>loop</arg>
<arg>blktap</arg>
</group></arg>
<sbr>
<arg choice="req">-t<group>
<arg>diskless</arg>
<arg>file</arg>
<arg>plain</arg>
<arg>drbd</arg>
</group>
......@@ -228,6 +235,12 @@
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>file</term>
<listitem>
<para>Disk devices will be regular files.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>plain</term>
<listitem>
......@@ -257,9 +270,61 @@
option.
</para>
<para>
The <option>--file-storage-dir</option> specifies the relative path
under the cluster-wide file storage directory to store file-based
disks. It is useful for having different subdirectories for
different instances. The full path of the directory where the disk
files are stored will consist of cluster-wide file storage directory
+ optional subdirectory + instance name. Example:
/srv/ganeti/file-storage/mysubdir/instance1.example.com. This option
is only relevant for instances using the file storage backend.
</para>
<para>
The <option>--file-driver</option> specifies the driver to use for
file-based disks. Note that currently these drivers work with the
xen hypervisor only. This option is only relevant for instances using
the file storage backend. The available choices are:
<variablelist>
<varlistentry>
<term>loop</term>
<listitem>
<para>Kernel loopback driver.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>blktap</term>
<listitem>
<para>blktap driver.</para>
</listitem>
</varlistentry>
<variablelist>
</para>
<para>
The loop driver uses loopback devices to access the filesystem
within the file. However, running I/O intensive applications
in your instance using the loop driver might result in slowdowns.
Furthermore, if you use the loopback driver consider increasing
the maximum amount of loopback devices (on most systems it's 8)
using the max_loop param.
</para>
<para>
In order to be able to use the blktap driver you should check
if the 'blktapctrl' user space disk agent is running (usually
automatically started via xend). This user-level disk I/O
interface has the advantage of better performance. Especially
if you use a network file system (e.g. NFS) to store your instances
this is the recommended choice.
</para>
<para>
Example:
<screen>
# gnt-instance add -t file -s 30g -m 512 -o debian-etch \
-n node1.example.com --file-storage-dir=mysubdir instance1.example.com
# gnt-instance add -t plain -s 30g -m 512 -o debian-etch \
-n node1.example.com instance1.example.com
# gnt-instance add -t drbd -s 30g -m 512 -o debian-etch \
......
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