<para>This setting replaces <varname>BlockIODeviceWeight=</varname> and disables settings prefixed with
<varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</para>
+
+ <para>The specified device node should reference a block device that has an I/O scheduler
+ associated, i.e. should not refer to partition or loopback block devices, but to the originating,
+ physical device. When a path to a regular file or directory is specified it is attempted to
+ discover the correct originating device backing the file system of the specified path. This works
+ correctly only for simpler cases, where the file system is directly placed on a partition or
+ physical block device, or where simple 1:1 encryption using dm-crypt/LUKS is used. This discovery
+ does not cover complex storage and in particular RAID and volume management storage devices.</para>
</listitem>
</varlistentry>
<para>These settings replace <varname>BlockIOReadBandwidth=</varname> and
<varname>BlockIOWriteBandwidth=</varname> and disable settings prefixed with <varname>BlockIO</varname> or
<varname>StartupBlockIO</varname>.</para>
+
+ <para>Similar restrictions on block device discovery as for <varname>IODeviceWeight=</varname> apply, see above.</para>
</listitem>
</varlistentry>
<para>These settings are supported only if the unified control group hierarchy is used and disable settings
prefixed with <varname>BlockIO</varname> or <varname>StartupBlockIO</varname>.</para>
+
+ <para>Similar restrictions on block device discovery as for <varname>IODeviceWeight=</varname> apply, see above.</para>
</listitem>
</varlistentry>
<para>Implies <literal>IOAccounting=yes</literal>.</para>
<para>These settings are supported only if the unified control group hierarchy is used.</para>
+
+ <para>Similar restrictions on block device discovery as for <varname>IODeviceWeight=</varname> apply, see above.</para>
</listitem>
</varlistentry>