esg1.umr-cnrm.fr fails for OpenDAP and wget downloads of CNRM-ESM2-1 6hrLev (ssp370)

[Linimie]

Hi ESGF team,

I'm encountering repeated access issues with the esg1.umr-cnrm.fr node while working with CNRM-ESM2-1 6hrLev ScenarioMIP data (ssp370, r1i1p1f2). This is affecting both OpenDAP access and direct file downloads via wget.

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🔍 Dataset context

I am using the following 6-hourly variables:

• ua, va, hus

✅ Historical data (1985–2015) — works fine:

OpenDAP via CEDA:
https://esgf.ceda.ac.uk/thredds/dodsC/esg_cmip6/CMIP6/CMIP/CNRM-CERFACS/CNRM-ESM2-1/historical/r1i1p1f2/6hrLev/

❌ ScenarioMIP (2019–2100) — unstable:

Forced to switch to:
http://esg1.umr-cnrm.fr/thredds/dodsC/CMIP6_CNRM/ScenarioMIP/CNRM-CERFACS/CNRM-ESM2-1/ssp370/r1i1p1f2/6hrLev/

OpenDAP access to this node fails in multiple ways:

• Datasets appear in ESGF search but OpenDAP access returns partial or corrupt data
• I switched to wget from the THREDDS fileServer endpoint, but download attempts still fail intermittently with:
  • wget exit status 8 — server error
  • Incomplete or zero-byte .nc files

These failures are non-deterministic: different files fail at different times, but the node is generally unstable.

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🧪 Reproducibility

My pipeline reproduces this issue consistently:

• ua_6hrLev_CNRM-ESM2-1_ssp370_r1i1p1f2_gr_201901010600-201905010000.nc is just one recent example, but other dates and variables have failed the same way

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🧰 Pipeline + Code

GitHub project:
🔗 https://github.com/UtrechtUniversity/ivt-pipeline-cnrm-arctic_cordex

Relevant download script:
🔗 https://github.com/UtrechtUniversity/ivt-pipeline-cnrm-arctic_cordex/blob/main/Download_wget_process_cmip6.py

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🙏 Request

Could the esg1.umr-cnrm.fr node be reviewed for:

• OpenDAP compatibility
• File availability and THREDDS stability for CNRM ScenarioMIP 6hrLev
• Mirroring to more reliable ESGF nodes (e.g., CEDA or DKRZ)

This issue is blocking reproducible access to a key dataset used for Arctic IVT projections and regridding.

Thanks in advance for your time and help!

Best regards,
Linda Gavras-van Garderen
UU-IMAU