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What to expect during a dry-run

Dry-runs are system sessions to simulate the DHS behaviour during the DHS Move. During a dry-run read access to the main DHS infrastructure located in Reading will be closed and instead essential data necessary to continue all critical activities during the move will be provided by a temporary DHS in Bologna.

Archive/Store operations will not be impacted and will continue as normal. Data archived during this period will be retrievable as normal.

At the start of the system session, all active/queued MARS retrieve requests and ECFS get operations on the DHS will fail. This is to switch MARS & ECFS to the dry-run configuration. After such failure, we encourage users to re-run requests/scripts once, to experience the expected behaviour during the DHS Move:

Requests for essential/recent data should be satisfied from the temporary DHS.
Requests for historical data should fail with an explanatory message. We encourage users to wait until the system session has ended before re-running requests for data known to be unavailable.

After the system session is over, user work can resume as normal

Timetable of System Session on 05 Apr 2022

Time (UTC)	Event	Impact	User action
8:00	Change configuration of all services using MARS/ECFS to point to the temporary DHS in Bologna.		Check service status
8:00 - 8:30	Drain all MARS/ECFS activity in DHS infrastructure in Reading	All active/queued MARS retrieve requests and ECFS get operations on the DHS in Reading will fail.	Please re-run to test behaviour expected during DHS Move.
8:30 - 17:30	DHS Move dry-run mode	Behaviour as expected during the DHS Move: only essential/recent data will be available	If the data you request is not available, wait until the end of the System Session before re-running failed requests.
18:00	Revert to use DHS infrastructure in Reading:	Short interruption.	Please re-run all failed requests/scripts.
18:00 -		Longer than usual turn-around time should be expected until back-log clears	Check service status

Log output samples of execution at various stages

When draining MARS activity in Reading

mars - INFO   - 20220331.170650 - Server task is 809 [marsod-core]
mars - ERROR  - 20220331.170650 - Mars server task finished in error
mars - ERROR  - 20220331.170650 - UserError: DHS infrastructure in Reading disabled. Please, re-run your request. If you see this message again for the same request, please, raise a ticket [marsod-core]
mars - ERROR  - 20220331.170650 - Error code is -2

When requesting data available in temporary DHS in Bologna

mars - INFO   - 20220331.165631 - Server task is 839 [temporary-dhs-prod]
mars - INFO   - 20220331.165631 - Request cost: N fields, BBBBBBBB Mbytes online, nodes: mvr007 [temporary-dhs-prod]
mars - INFO   - 20220331.165631 - Transfering BBBBBBBBB bytes
mars - INFO   - 20220331.165631 - N fields retrieved from 'temporary-dhs'

When requesting data not available during the DHS Move

mars - INFO   - 20220331.144749 - Server task is 614 [bologna-marsod-blank]
mars - ERROR  - 20220331.144749 - Mars server task finished in error
mars - ERROR  - 20220331.144749 - AccessError: This data exists but will be unavailable during the DHS Move. For more information see https://confluence.ecmwf.int/x/jSKADQ [bologna-marsod-blank]
mars - ERROR  - 20220331.144749 - Error code is -2

Available tools

MARS

Data available during the DHS Move dry-run is listed in the Catalogue of the temporary DHS.
To monitor the status of your requests during the DHS Move dry-run, please, visit the Temporary DHS server activity.

How to report a problem

If your activity is critical and we have missed to identify it as such, please raise a support ticket, see below, and we will look at your specific requirements.

If your request/command does not behave as described above, please, provide as much information as possible so analysts can investigate/reproduce the problem, for example:

Service/Tool you are using (mars client, ecfs, metview, web api, verify, etc...)
Version of the tool
Host, such as, ecgb, ATOS, cca, your workstation, ... and the environment under which it runs, interactive, batch, ...
Log output produced by MARS/ECFS, including the request

Please report all issues via our Support Portal, mentioning "dhs dry-run" in the title of your computing problem ticket.