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NEWS!

Further change to transition plan. Expected main service disruptions updated.

Change to original transition plan. Expected main service disruptions updated. Further update to transition plan will be provided by end of October.


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 below 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 data necessary to continue operational and time-critical activities at ECMWF, with the aim to minimise the impact of the DHS move. After 6 days we will start filling 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, a new main DHS will become operational 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. Two longer dry-runs, lasting 5-7 days, the second one expected to happen 4 weeks before the move, 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.

EventDateDurationImpact
Dry-run 1December 2021, TBC12 hoursaccess limited to available data
Dry-run 2December 2021, TBC24 hoursaccess limited to available data
............
Reduced service dry-run1 month before the DHS-Move, TBC5-7 daysaccess limited to available data
DHS-Movelate February / early March 2022, TBC28 days

access limited to available data, all archive content becoming gradually available again during the move

Summary of impact by user group

This table highlights how specific user groups will be affected by the DHS-Move. See further below for more details on the availability of specific data.

User groupImpact
Member State User (fully registered computer user)

mars-client/WebAPI/ECFS - Access limited to available data 
mars-client/WebAPI - No access to historical operational data and IFS research experiments
mars-client/WebAPI - No access to public datasets (TIGGE, S2S, etc.)

Web User (registered by MS)

WebAPI - Access limited to available data 
WebAPI - No access to historical operational data and IFS research experiments
WebAPI - No access to public datasets (TIGGE, S2S, etc.) 

Commercial and research user (maxch*, comarc*, resarc*, nm*)

WebAPI - No access to historical operational data and IFS research experiments
WebAPI - No access to public datasets (TIGGE, S2S, etc.) 

Public users

WebAPI - No access to public datasets (TIGGE, S2S, etc.) 
ADS/CDS - No access to data served from MARS tapes


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 list of available data, not expected to be impacted during dry-runs and the DHS-Move, will be updated in light of further migration progress: 

The following services are not expected to be impacted by dry-runs and the DHS-Move:

  • Archiving into MARS
  • MS Time-critical suites
  • Atos HPC testing


Unavailability of service/data

Any data not listed as available during dry-runs and the DHS-Move will not be accessible, in particular:

Impact to ECFS service

During dry-runs and the DHS-Move ECFS will be impacted as follows:

No impact expected

The following list of available data, not expected to be impacted during dry-runs and the DHS-Move, will be updated in light of further migration progress: 

  • Recent output (~ one month) from operational production systems
  • Observations
  • Any data written during dry-runs and DHS-Move

The following services are not expected to be impacted by dry-runs and the DHS-Move:

  • Writing into ECFS
  • All 'metadata' operations (listing, renames, moves, deletions, changing ownership/permissions).
  • MS Time-critical suites
  • Atos HPC testing
Unavailability of service/data

The following services/data will not be available during dry-runs and the DHS-Move:

  • Any data not listed as available above, in particular IFS Research experiment data  and historical operational data. For data offline the first character in the output of the 'els -l' command will be replaced with 'o'.

The commands ecp, emv and ecat accessing data which are not available will fail with a 'Data Offline' error without retrying. 


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...
  • ECMWF computer users missing access to data for any critical activity during the DHS-Move should contact us at their earliest convenience with their requirements via the ECMWF Support Portal.
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