1 Functional Requirements
2 -----------------------
7 This section describes the basic functions may required by Escalator.
12 This is the design phase when the upgrade plan (or upgrade campaign) is
13 being designed so that it can be executed automatically with minimal
14 service outage. It may include the following work:
16 1. Check the dependencies of the software modules and their impact,
17 backward compatibilities to figure out the appropriate upgrade method
19 2. Find out if a rolling upgrade could be planned with several rolling
20 steps to avoid any service outage due to the upgrade some
21 parts/services at the same time.
22 3. Collect the proper version files and check the integration for
24 4. The preparation step should produce an output (i.e. upgrade
25 campaign/plan), which is executable automatically in an NFV Framework
26 and which can be validated before execution.
28 - The upgrade campaign should not be referring to scalable entities
29 directly, but allow for adaptation to the system configuration and
30 state at any given moment.
31 - The upgrade campaign should describe the ordering of the upgrade
32 of different entities so that dependencies, redundancies can be
33 maintained during the upgrade execution
34 - The upgrade campaign should provide information about the
35 applicable recovery procedures and their ordering.
36 - The upgrade campaign should consider information about the
37 verification/testing procedures to be performed during the upgrade
38 so that upgrade failures can be detected as soon as possible and
39 the appropriate recovery procedure can be identified and applied.
40 - The upgrade campaign should provide information on the expected
41 execution time so that hanging execution can be identified
42 - The upgrade campaign should indicate any point in the upgrade when
43 coordination with the users (VNFs) is required.
45 .. <hujie> Depends on the attributes of the object being upgraded, the
46 upgrade plan may be slitted into step(s) and/or sub-plan(s), and even
47 more small sub-plans in design phase. The plan(s) or sub-plan(s) my
48 include step(s) or sub-plan(s).
50 Validation the upgrade plan / Checking the pre-requisites of System( offline / online)
51 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
53 The upgrade plan should be validated before the execution by testing
54 it in a test environment which is similar to the product environment.
56 .. <MT> However it could also mean that we can identify some properties
57 that it should satisfy e.g. what operations can or cannot be executed
58 simultaneously like never take out two VMs of the same VNF.
60 .. <MT> Another question is if it requires that the system is in a particular
61 state when the upgrade is applied. I.e. if there's certain amount of
62 redundancy in the system, migration is enabled for VMs, when the NFVI
63 is upgraded the VIM is healthy, when the VIM is upgraded the NFVI is
66 .. <MT> I'm not sure what online validation means: Is it the validation of the
67 upgrade plan/campaign or the validation of the system that it is in a
68 state that the upgrade can be performed without too much risk?==
70 Before the upgrade plan being executed, the system healthy of the
71 online product environment should be checked and confirmed to satisfy
72 the requirements which were described in the upgrade plan. The
73 sysinfo, e.g. which included system alarms, performance statistics and
74 diagnostic logs, will be collected and analogized. It is required to
75 resolve all of the system faults or exclude the unhealthy part before
76 executing the upgrade plan.
79 Backup/Snapshot (online)
80 ^^^^^^^^^^^^^^^^^^^^^^^^
82 For avoid loss of data when a unsuccessful upgrade was encountered, the
83 data should be back-upped and the system state snapshot should be taken
84 before the execution of upgrade plan. This would be considered in the
87 Several backups/Snapshots may be generated and stored before the single
88 steps of changes. The following data/files are required to be
91 1. running version files for each node.
92 2. system components' configuration file and database.
93 3. image and storage, if it is necessary.
95 .. <MT> Does 3 imply VNF image and storage? I.e. VNF state and data?==
97 .. <hujie> The following text is derived from previous "4. Negotiate
98 with the VNF if it's ready for the upgrade"
100 Although the upper layer, which include VNFs and VNFMs, is out of the
101 scope of Escalator, but it is still recommended to let it ready for a
102 smooth system upgrade. The escalator could not guarantee the safe of
103 VNFs. The upper layer should have some safe guard mechanism in design,
104 and ready for avoiding failure in system upgrade.
109 The execution of upgrade plan should be a dynamical procedure which is
110 controlled by Escalator.
112 .. <hujie> Revised text to be general.==
114 1. It is required to supporting execution ether in sequence or in
116 2. It is required to check the result of the execution and take the
117 action according the situation and the policies in the upgrade plan.
118 3. It is required to execute properly on various configurations of
119 system object. I.e. stand-alone, HA, etc.
120 4. It is required to execute on the designated different parts of the
121 system. I.e. physical server, virtualized server, rack, chassis,
122 cluster, even different geographical places.
127 The testing after upgrade the whole system or parts of system to make
128 sure the upgraded system(object) is working normally.
130 .. <hujie> Revised text to be general.
132 1. It is recommended to run the prepared test cases to see if the
133 functionalities are available without any problem.
134 2. It is recommended to check the sysinfo, e.g. system alarms,
135 performance statistics and diagnostic logs to see if there are any
138 Restore/Roll-back (online)
139 ^^^^^^^^^^^^^^^^^^^^^^^^^^
141 When upgrade is failure unfortunately, a quick system restore or system
142 roll-back should be taken to recovery the system and the services.
144 .. <hujie> Revised text to be general.
146 1. It is recommend to support system restore from backup when upgrade
148 2. It is recommend to support graceful roll-back with reverse order
154 Escalator should continually monitor the process of upgrade. It is
155 keeping update status of each module, each node, each cluster into a
156 status table during upgrade.
158 .. <hujie> Revised text to be general.
160 1. It is required to collect the status of every objects being upgraded
161 and sending abnormal alarms during the upgrade.
162 2. It is recommend to reuse the existing monitoring system, like alarm.
163 3. It is recommend to support pro-actively query.
164 4. It is recommend to support passively wait for notification.
166 **Two possible ways for monitoring:**
168 **Pro-Actively Query** requires NFVI/VIM provides proper API or CLI
169 interface. If Escalator serves as a service, it should pass on these
172 **Passively Wait for Notification** requires Escalator provides
173 callback interface, which could be used by NFVI/VIM systems or upgrade
174 agent to send back notification.
176 .. <hujie> I am not sure why not to subscribe the notification.
181 Record the information generated by escalator into log files. The log
182 file is used for manual diagnostic of exceptions.
184 1. It is required to support logging.
185 2. It is recommended to include time stamp, object id, action name,
188 Administrative Control (online)
189 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
191 Administrative Control is used for control the privilege to start any
192 escalator's actions for avoiding unauthorized operations.
194 #. It is required to support administrative control mechanism
195 #. It is recommend to reuse the system's own secure system.
196 #. It is required to avoid conflicts when the system's own secure system
199 Requirements on Object being upgraded
200 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
202 .. <hujie> We can develop BPs in future from requirements of this section and
203 gap analysis for upper stream projects
205 Escalator focus on smooth upgrade. In practical implementation, it
206 might be combined with installer/deplorer, or act as an independent
207 tool/service. In either way, it requires targeting systems(NFVI and
208 VIM) are developed/deployed in a way that Escalator could perform
211 On NFVI system, live-migration is likely used to maintain availability
212 because OPNFV would like to make HA transparent from end user. This
213 requires VIM system being able to put compute node into maintenance mode
214 and then isolated from normal service. Otherwise, new NFVI instances
215 might risk at being schedule into the upgrading node.
217 On VIM system, availability is likely achieved by redundancy. This
218 impose less requirements on system/services being upgrade (see PVA
219 comments in early version). However, there should be a way to put the
220 target system into standby mode. Because starting upgrade on the
221 master node in a cluster is likely a bad idea.
223 .. <hujie>Revised text to be general.
225 1. It is required for NFVI/VIM to support **service handover** mechanism
226 that minimize interruption to 0.001%(i.e. 99.999% service
227 availability). Possible implementations are live-migration, redundant
228 deployment, etc, (Note: for VIM, interruption could be less
231 2. It is required for NFVI/VIM to restore the early version in a efficient
232 way, such as **snapshot**.
234 3. It is required for NFVI/VIM to **migration data** efficiently between
235 base and upgraded system.
237 4. It is recommend for NFV/VIM's interface to support upgrade
238 orchestration, e.g. reading/setting system state.