CVMFS Stratum-0 Availability and Continuity Plan
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This page reports on the Availability and Continuity Plan for the CVMFS Stratum-0 and it is the result of the risks assessment conducted for this service: a series of risks and treats has been identified and analysed, along with the correspondent countermeasures currently in place. Whenever a countermeasure is not considered satisfactory for either avoiding or reducing the likelihood of the occurrence of a risk, or its impact, it is agreed with the service provider a new treatment for improving the availability and continuity of the service. The process is concluded with an availability and continuity test.
previous plans are collected here: https://documents.egi.eu/document/3849
Availability requirements and performances
- CernVM-FS is a file system with a single source of data. This single source, the repository Stratum-0, is maintained on a dedicated release manager machine or CVMFS Uploader.
- The CVMFS Uploader is hosted by a server that offers read-write access to the repository maintainers via a GSI interface.
In the OLA it was agreed the following performances targets, on a monthly basis:
- Availability: 95%
- Reliability: 97%
The service availability is regularly tested by nagios probes org.nagiosexchange.CVMFS-WebCheck: https://argo-mon.egi.eu/nagios/cgi-bin/status.cgi?servicegroup=SITE_GRIDOPS-CVMFS_ch.cern.cvmfs.stratum.0&style=overview
Over the past years, the EGI Content Distribution / CVMFS Startum-0 hadn't particular Av/Co issues highlighted by the performances that need to be further investigated.
Risks assessment and management
For more details, please look at the google spreadsheet. We will report here a summary of the assessment.
|Risk id||Risk description||Affected components||Established measures||Risk level||Expected duration of downtime / time for recovery||Comment|
|1||Service unavailable / loss of data due to hardware failure||Stratum-0||Given the architecture of the service, end users are not impacted, as they don't get the data from the CVMFS Stratum-0 but from the replicas (Stratum-1s).||Low||1 or more working days, depending on repare or replacement of hardware.||the measures already in place are considered satisfactory and risk level is acceptable|
|2||Service unavailable / loss of data due to software failure||Stratum-0||Given the architecture of the service, end users are not impacted, as they don't get the data from the CVMFS Stratum-0 but from the replicas (Stratum-1s).||Low||If data needs to be recovered, 1 working day.||the measures already in place are considered satisfactory and risk level is acceptable|
|3||service unavailable / loss of data due to human error||Stratum-0||Reduce the impact: service configuration is in the Configuration Management System, making human error easy to roll back.||Low||If data needs to be recovered, 1 working day.||the measures already in place are considered satisfactory and risk level is acceptable|
|4||service unavailable for network failure (Network outage with causes external of the site)||Stratum-0||None||Low||The duration of the network outage.||the measures already in place are considered satisfactory and risk level is acceptable|
|5||Unavailability of key technical and support staff (holidays period, sickness, ...)||Stratum-0||A cover person, capable of handling tickets and investigating problems, is assigned in the case
of short term absences. Service setup and troubleshooting recipes are documented.
|Low||The length of the absence / declared downtime.||the measures already in place are considered satisfactory and risk level is acceptable|
|6||Major disruption in the data centre. Fire, flood or electric failure for example||Stratum-0||Reduce the likelihood: The health of the data centre is proactivly managed by a team of experts. Reduce the impact: The CVMFS servers run on UPS, so should remain operational in the event of electrical failure. In the case of other, long lasting, data centre disruption, the failover would be engaged.||Low||Depends on the details of the incident.||the measures already in place are considered satisfactory and risk level is acceptable|
|7||Major security incident. The system is compromised by external attackers and needs to be reinstalled and restored.||Stratum-0||Reduce the likelihood: Internal security audits of the CVMFS machines that (for example) ensure packages are up to date, only the necasary ports are open, vunerbalilty warnings are recieved, etc. Reduce the impact: Use of configuration management means reinstalling, restoring or deployment of a new instance of a CVMFS Stratum-0 host to a known state can be done quickly. Data can be recovered from backup.||Low||Depends on the details of the incident.||the measures already in place are considered satisfactory and risk level is acceptable|
|8||(D)DOS attack. The service is unavailable because of a coordinated DDOS.||Stratum-0||Reduce the likelihood: the web server is configured to listen to a non-standard port, 8000 instead of 443.
Reduce the impact: The number of requests over time are monitored so any abnormal increase in traffic or response time would be noticed.
|Low||Depends on the details of the incident.||the measures already in place are considered satisfactory and risk level is acceptable|
The level of all the identified risks is acceptable and the countermeasures already adopted are considered satisfactory
- The Tier-1 hosting the service has a protocol for disaster management. The administrators will follow the steps on that planning in case of risks occurrence.
- The Availability targets don't change in case the plan is invoked.
- Recovery requirements (outcomes of the Business Impact Analysis).
- Maximum tolerable period of disruption (MTPoD) (the maximum amount of time that a service can be unavailable or undelivered after an event that causes disruption to operations, before its stakeholders perceive unacceptable consequences): 1 week
- Recovery time objective (RTO) (the acceptable amount of time to restore the service in order to avoid unacceptable consequences associated with a break in continuity (this has to be less than MTPoD)): 5 days
- Recovery point objective (RPO) (the acceptable latency of data that will not be recovered): 1 day
- Approach for the return to normal working conditions as reported in the risk assessment.
- The support unit Software and Data Distribution (CVMFS) shall be used to report any incident or service request
- The providers can contact EGI Operations via ticket or email in case the continuity plan is invoked, or to discuss any change to it.
Availability and Continuity test
Considering the outcome of the Business Impact Analysis and of the Risk Assessment, there is no need of an A&C test: the service can be restored within the expected timeline in case of disruptions.
|Renato Santana||2021-10-28||first draft|
|Renato Santana||2021-12-01||risk analysis edition|
|Alessandro Paolini||2021-12-03||plan finalised, no need of A/C test|