Transition plan
The Data Handling System (DHS), providing the MARS and ECFS services, needs to be moved to Bologna before the new Atos HPCF will produce an increased archive load. A detailed migration timeline is shown in the transition plan where all events are relative to day D, the day when the MARS and ECFS service will stop accessing the Main-DHS-Reading. Instead the MARS and ECFS service will be provided by a temporary DHS which has been pre-filled with essential data, necessary to continue operational and time-critical activities, to minimise the impact of the DHS move. After 6 days we will start to fill the new Main-DHS-Blank with the data from the Temporary-DHS-prod and from the Main-DHS-Reading. At the end of the DHS-Move, expected to take 28 days, there will be a new operational DHS in Bologna. In preparation of the DHS move we will conduct a number of dry-runs, during which the access to the main DHS in Reading will be blocked. The purpose of the dry runs is to verify that the Temporary-DHS does contain all essential data necessary to continue all critical activities during the move. Some of the dry-runs will last for 1-2 days. A final longer dry-run, lasting 5-7 days, is expected to happen 4 weeks before the move and will help to establish the exact date of day D.
Main service disruptions
The table below gives an indication of disruptions to the MARS and ECFS service foreseen as part of the DHS-Move.
| Event | Date | Duration | Impact |
|---|---|---|---|
| Dry-run 1 | September 2021, TBC | 12 hours | degraded access to non-essential data |
| Dry-run 2 | September 2021, TBC | 24 hours | degraded access to non-essential data |
| ... | ... | ||
| Final dry-run | October 2021, TBC | 5-7 days | degraded access to non-essential data |
| DHS-Move | November 2021, TBC | 28 days | degraded access to non-essential data, with data becoming gradually available again during the move |
Summary of impact by user group
| User group | Impact |
|---|---|
| Member State User (fully registered computer user) | mars-client/WebAPI/ECFS - limited to essential data |
| Web User (registered by MS) | WebAPI - limited to essential data |
| Commercial and research user (maxch*, comarc*, resarc*, nm*) | WebAPI - No access to historical operational data and IFS research experiments |
| Public users | WebAPI - No access to public datasets (TIGGE/S2S, etc.) |
Commercial users (comarc_*) with a valid licence during the outage will have the equivalent length of the outage added to their existing contract length.
Users may also opt to terminate their licence with 4 weeks notice.
Impact to MARS service
No impact expected
The following essential services/data are not expected to be impacted by the dry-runs and the DHS-Move:
- Recent output (~ one month) from operational production systems: All products listed in the Catalogue of ECMWF real-time products, ERA5T (near real-time), CAMS, …
Observations, analysis input, tropical cyclones for the entire period
ERA5 data required as initial conditions for the operational hindcasts (20 years for the relevant weeks)
- Archiving into MARS
- MS Time-critical suites
- Atos HPC testing
Access to non-essential services/data will be affected as described below.
Degradation of service/data access
Non-essential services and access to data degraded during dry-runs and the DHS-Move:
- Retrieval via the WebAPI by MS-registered and commercial users will be limited to the essential data listed above
- Retrieval via the MARS client on ECMWF computers will be limited to the essential data listed above
Unavailability of service/data
The following services/data will not be available during dry-runs and the DHS-Move:
- Public datasets
- ADS/CDS data served by MARS
- IFS Research experiments
- Historical operational data, non-essential ERA5 data
Impact to ECFS service
During dry-runs and the DHS move access to data archived in ECFS which has not been identified as essential will not be available. However, archiving into ECFS should not be affected by the DHS migration.
Recommended user action
- Users of MARS and ECFS are urged to check if and how their work might be affected by the DHS-Move and plan accordingly.
- Major changes to production processes etc. are best avoided during this period. For some activities the best course of action might be to avoid the migration period entirely...
- Users missing access to data for any critical activity during the DHS-move should contact ServiceDesk at their earliest convenience with their requirements.