No, there will be changes to the  file-naming convention, see Dissemination file-naming changes from IFS Cycle 49r1 to 50r1

Yes, due to the nature of the upgrade, ECMWF will transfer all installed requirements in the test PREd to the production system on the day of the cycle implementation. During the RCP, any changes made in the production system should also be installed in the test system to ensure continuity.  

• If you're a Basic/Bronze user, the Data Support team can push a test batch of IFS Cycle 50r1 data to the host configuration.
• If you're a Silver/Gold user, then you can either push the data to yourself or set the data to be delivered in 'NORMAL' mode. If you put the data in 'NORMAL' mode, the data will be disseminated to your host automatically. However, the data are disseminated between operational windows to protect network capacity, meaning the data will not be disseminated according to the usual dissemination schedule. There is no fixed delivery schedule, and products may not be available in real time, delays of up to one day are possible.

The data are disseminated between operational windows to protect network capacity. There is no fixed delivery schedule, and products may not be available in real time, delays of up to one or days are possible.
Usually as we get close to implementation the delay gets smaller.

The same TOTP token should be used for the xdiss as for the diss system.

No, the test data are strictly for non-operational use. Test products are intended for internal testing and validation only and must not be used in operational services or shared on social media.

In the test PREd (TPred), you will be able to test as much data as you want (even over your current Volume Band), however when it comes to operational day, if you have made changes that are over your current Volume Band, you will need to do an amendment to your current contract.

No, this will not work. You should use the TPREd to install test data.

You can only do this if you have the Silver or Gold service package. 

Login to the test ECPDS (XDISS: https://xdiss-monitor.ecmwf.int/) and follow the instructions for pushing data to yourself here: https://confluence.ecmwf.int/pages/viewpage.action?pageId=228871373

Not necessarily. The host configuration of the test system might not be in sync with the operational system. You also might want to receive the data files at a different endpoint. In case, you would like to make changes, please indicate this in the form: RCP 50r1 - Test System User Details or contact us via https://support.ecmwf.int

IFS Cycle 50r1 beta test data is available from MARS with E-suite experiment version (expver) 0080 (MARS keywords EXPVER=0080, CLASS=OD). However, these data are not open to commercial users.

Indeed, the control will be disseminated earlier. See the control forecast schedule in this page: Dissemination schedule 

For IFS Cycle 50r1, Ensemble Control forecast (ENS-cf) will become oper-fc and will not have perturbationNumber=0. The plan is to change this in IFS Cycle 50r2, with the GRIB2 migration. 

Yes, we will provide re-forecast products to allow creation of a model climate for both medium-range and extended-range. This will be provided in the next few weeks and more information will follow when they are available. 

Yes, if you would like to switch to the new file naming convention, you can test it in the test PREd (TPREd) environment during the IFS Cycle 50r1 Release Candidate phase.

The current 'legacy' file naming convention will remain available for some time, including after the 50r1 implementation. However, you will need to migrate to the ECMWF file naming convention later this year, as described here:
https://confluence.ecmwf.int/display/DAC/File+naming+convention+and+format+for+real-time+data#Filenamingconventionandformatforrealtimedata-Naming-AIFSviadissemination

If you are already updating your scripts, it would be a good opportunity to switch to the 'ECMWF' file naming convention at the same time.

For Basic and Bronze users, once you've confirmed that you're "Ready to Migrate" with the Data Support team, on the day of implementation, the esuite (TPREd) will become the operational (PREd).
This means all the data requirement changes that were done to test yourI FS Cycle 50r1 data requirements, will start to be delivered operationally.

 AIFS has a separate update cycle from the IFS, but they are synchronised this time. Head over to Implementation of AIFS Single v2 and Implementation of AIFS ENS v2 for more info.

We would encourage this, yes. In the IFS Cycle 49r1, (ex) HRES and Ensemble Control are numerically identical. If the users make this change at IFS Cycle 49r1, then they won't need to make it at IFS Cycle 50r1.

In IFS Cycle 50r1 it will still be a blend of GRIB1 and GRIB2. Full migration to all GRIB2 will happen with IFS Cycle 50r2, planned for implementation in late 2026, with plenty of test data available during the year or so leading up to this. Read more in this article from Spring 2023 Newsletter and In Focus article:  Migration to GRIB2 data format: implications for users.

We are not planning to replace GRIB2 in the near future.

No, we will not be forcing users to migrate to the CCSDS compression with the IFS Cycle 50r1 update. However, we strongly recommend testing and switching to the CCSDS compression.