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======Update guide======
<note important>
Starting from version [[en:dpi:changelog:versions:ver_12|12.0]], DPI is supported **only** on CentOS 8.x and [[en:veos:installation|veos]].
</note>

=====Preparation for update=====
  * Make sure that the DPI configuration and dependent services (pcrf, radius) are valid.
  * Check the currently installed version:<code bash>yum info fastdpi</code>
  * If CentOS 8.x is used, **once** switch repositories to vault:<code bash>sed -i -e '/^mirrorlist=http:\/\//d' -e 's/^# *baseurl=http:\/\/mirror.centos.org/baseurl=http:\/\/vault.centos.org/' /etc/yum.repos.d/CentOS-*.repo</code>
  * If there are dependency issues or the update cannot be found, run:<code bash>yum clean all</code>

=====Special operating conditions=====
**For virtual machines, old processors (approximately before 2009), and old amd processors (before ryzen):**

Before updating, run:
<code bash>
touch /etc/dpi/noprioadj
</code>

In this case, DPI will start with a normal (non-realtime) priority, which reduces cpu (sys) load but may slightly increase latency.

=====DPI update=====
  * Main version update:<code bash>yum update fastdpi</code>
  * Installation of a test (beta) version:<code bash>yum --enablerepo vasexperts-beta update fastdpi</code>

<note tip>
If the ''module yaml error'' occurs during update, update the module: <code bash>dnf upgrade libmodulemd</code>
</note>

=====Service restart=====

After updating or changing the version, **be sure** to restart DPI:
<code bash>
service fastdpi restart
</code>

If PCRF and/or radius are used, they must also be restarted (only with a valid configuration):
<code bash>
service fastpcrf restart
service fdpi_radius restart
</code>

**Recommended pcrf restart order:**
<code bash>
service fastdpi stop
service fastpcrf restart
service fastdpi start
</code>

=====Operating system update=====

<note important>
Do not update the linux kernel version and kernel-dependent utilities.
</note>

  * For CentOS 8.x:<code bash>yum update</code>

=====Version rollback=====

  * Example rollback to version 14.0:<code bash>yum downgrade fastdpi-14.0 fastpcrf-14.0 dpiutils-14.0 fastradius-14.0</code>
  * Example rollback to version 12.4:<code bash>yum downgrade fastdpi-12.4-0 fastpcrf-12.4-0</code>

After rollback, service restart is required:
<code bash>
service fastdpi restart
</code>

=====Important notes=====
  * Customers using bras functionality must take changes into account when upgrading to new versions.
  * Updating the linux kernel may break binary compatibility with kernel abi and cause issues with network driver loading.
  * If the kernel was updated, temporarily configure booting the previous version via grub by setting the required ''default'' parameter value in the ''/etc/grub.conf'' file.