====== Migrating from CentOS to VEOS ======
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===== Migrating from CentOS 8 to VEOS (VAS Experts OS) =====
<note important>Due to the fact that Red Hat discontinued support for CentOS 8 at the end of 2021, VAS Experts offers a strategy for the continued use of Red Hat as Control Plane.\\
**The transition to the new OS edition is planned in the form of an in-house upgrade (without reinstallation), [[dpi:techsupport_info|within the framework of active technical support]].**</note>

===== Migrating from CentOS 6 to VEOS =====
<note important> Why migrate from CentOS 6? \\
Discontinued the release of updates for CentOS 6, which may be critical to security when using this OS. \\
Discontinued the release of SSG DPI versions for CentOS 6, the latest version 11.x.
</note>

**1. Back up your configuration and license files **, UDR: \\

<code>
mdb_copy /var/db/dpi/ /etc/dpi/
tar -cvf dpi_config.tar /etc/dpi
rm /etc/dpi/data.mdb</code>

**2. [[veos:installation|Install and configure the VEOS as instructed]].**\\
**3. Upload the backups ** to the server. \\
**4. To install SSG, please contact the support service ** by sending an email to sd@vas.expert with SSH access credentials. Specify the location where you placed the backups.

<note important> To ensure the continuity of the service, it is possible to use a backup server to update the OS and software version on the main:
\\
\\
  * Prepare the second server according to clause 2, install it in the network parallel to the main one.
  * Transfer a copy of the configuration from item 1 to the second server.
  * To install SSG software, send a message to sd@vas.expert. Specify the location where you placed the backups.
  * The second server will have a ** temporary license for a period of one month **.
  * During this period, complete steps 1-4 on the primary server.
  * After installing Stingray SG and loading the configuration on the main server, transfer the traffic back to the main server.
  * ** After a month, the license on the second server will be canceled **.

To increase the system's fault tolerance, we recommend purchasing [[dpi:licensing#reserve_ssg_license|perpetual backup license]].
</note>