forked from docs/blueprints
87 lines
3.9 KiB
ReStructuredText
87 lines
3.9 KiB
ReStructuredText
Rehost
|
|
~~~~~~
|
|
|
|
Rehost, also known as **lift and shift**, is the most common way to
|
|
migrate applications to the cloud without changing the running
|
|
environment of applications. It is usually used for Physical to Virtual
|
|
(P2V) and Virtual to Virtual (V2V) scenarios. It can help companies
|
|
quickly migrate applications such as SAP, ERP, and CRM to the cloud.
|
|
|
|
Open Telekom Cloud provides three rehosting solutions:
|
|
|
|
Application redeployment
|
|
************************
|
|
|
|
In this solution, applications can be redeployed on ECSs or BMSs. This
|
|
solution is ideal for stateless applications that do not involve data
|
|
migration. The OSs of cloud servers can be changed as needed, for
|
|
example, if an old OS is no longer supported. This solution is
|
|
recommended when a new OS is required, but this means the applications
|
|
will be offline for a time.
|
|
|
|
Image import & export
|
|
*********************
|
|
|
|
By exporting system images of source servers and then importing those
|
|
images to the cloud as private images, you can quickly create cloud
|
|
servers with the same OSs and other details as your legacy servers. This
|
|
solution is a good choice when you need to migrate on-premises servers
|
|
that do not have too much data on them. The servers will have the same
|
|
OSs before and after the migration, but there will be a fair bit of
|
|
downtime.
|
|
|
|
Server Migration Service (SMS)
|
|
******************************
|
|
|
|
SMS can migrate applications to the cloud and synchronize incremental
|
|
data to minimize the downtime. However, the OS cannot be upgraded during
|
|
the migration.
|
|
|
|
+--------------+---------------------+---------------------------------+
|
|
| Object | Migration Method | Pros and Cons |
|
|
+==============+=====================+=================================+
|
|
| Virt | Redeployment | - Easy OS change |
|
|
| ual/physical | | |
|
|
| servers | | - Long downtime |
|
|
+--------------+---------------------+---------------------------------+
|
|
| | Image import & | - OS consistency |
|
|
| | export | |
|
|
| | | - Long downtime |
|
|
+--------------+---------------------+---------------------------------+
|
|
| | SMS | - OS consistency |
|
|
| | | |
|
|
| | | - Long downtime |
|
|
+--------------+---------------------+---------------------------------+
|
|
|
|
Take a typical three-layer application architecture as an example. The
|
|
following figure shows how the architecture is different before and
|
|
after the migration.
|
|
|
|
.. image:: ../../assets/caf/image45.png
|
|
|
|
Rehost has the following benefits:
|
|
|
|
- The application architecture is consistent before and after the
|
|
migration, so you know the original technology stack still work.
|
|
Rehosting ensures the migration of your applications can go smoothly.
|
|
- If the databases were built using Open Telekom Cloud ECS, the database
|
|
licenses can be reused in commercial database scenarios to save
|
|
money.
|
|
- Applications are deployed across AZs, so you can configure DC-level
|
|
HA.
|
|
- With Open Telekom Cloud ELB and Auto Scaling, services can be flexibly
|
|
scaled to adapt to workload changes.
|
|
- ELB replaces traditional offline hardware load balancing devices and
|
|
the network ACLs replace traditional hardware firewalls, further
|
|
reducing the hardware investments required.
|
|
- The O&M is simpler. CES provides comprehensive O&M monitoring of
|
|
cloud infrastructure, and LTS provides quick collection and analysis
|
|
of application logs.
|
|
- The reliability is enhanced. CBR backs up cloud servers for restore
|
|
or other server issues.
|
|
- The security is hardened. HSS protects cloud servers, WAF filters web
|
|
application traffic, and DBSS hardens cloud databases.
|
|
|
|
.. toctree::
|
|
:maxdepth: 1
|