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--- habrok:migration:faq [2024/03/28 13:04] – Add instructions for compiling code with the correct instruction set pedro
+++ habrok:migration:faq [2025/03/14 15:20] (current) – [New server hostkey] Add link to Host Keys page pedro
@@ Line 2: / Line 2: @@
 ===== FAQ =====
-==== Will my Peregrine account work on Hábrók? ====
+==== How do I solve a processor or OS not supporting certain instructions? ====
-Because there are quite a number of inactive accounts on Peregrine, we have decided not to automatically migrate the accounts to Hábrók, so your account on Peregrine will not automatically work on Hábrók.
+**Short answer**: ensure you compile your program on the same CPU architecture as the compute node you will then run it on.
-If you want to use the new cluster, you need to request access to it by using the  [[https://iris.service.rug.nl/|Self-Service Portal IRIS]].
+You may run across an error when you try to run an application that tells you the operating system or processor does not support certain instructions. This is often accompanied by a list of acronyms which correspond to the instructions. This is an example error message:
-Please go to Research and Innovation Support → Computing and Research Support Facilities → High Performance Computing Cluster → Request Hábrók Account.
+<code>
+Please verify that both the operating system and the processor support Intel(R) X87, CMOV, MMX, FXSAVE, SSE, SSE2, SSE3, SSSE3, SSE4_1, SSE4_2, MOVBE, POPCNT, AVX, F16C, FMA, BMI, LZCNT, AVX2, AVX512F, AVX512DQ, ADX, AVX512CD, AVX512BW and AVX512VL instructions.
+</code>
-==== Will my data be automatically moved from Peregrine to Hábrók? ====
+This happens because your program was compiled in a system that supports these instructions, but is running in a system that doesn't. Most likely you may have compiled your program on a different node than the one you are running your program from.
-We will not automatically move your data from Peregrine to Hábrók. The filesystems on Peregrine, ''/home'' and ''/data'' will be made available read-only on Hábrók for three months after Peregrine shuts down. You will have this time to move your data to permanent storage on Habrok.
+To get around this, you can make sure you compile your program in the same system that it will run. For example: if you need to run your program on one of the ''himem'' nodes, then you can submit a job that compiles your program, and subsequent jobs that then use the resulting executables to run your program. Alternatively, you can start an interactive session on a node with the target CPU architecture and compile your code interactively there. For example, assuming you want to compile your program for the ''himem'' nodes you could do ''srun --time=01:00:00 --partition=himem --pty /bin/bash''. This will queue an interactive session lasting up to one hour on which you can compile your code.
-**The data on Peregrine /scratch will not be migrated, since it is temporary space only.**
+==== New server hostkey ====
-==== How do I migrate data to Habrok? ====
+In order to bring Hábrók back online after an incident we sometimes have to reinstall and reconfigure the login and interactive nodes. Because of this, these nodes will have new server host keys. This means that connecting to Hábrók results in (correct) warnings that these keys no longer match those that had been registered on your system when you connected for the first time.
-The best tool for copying data from one location to the other is ''rsync''. Here is an example showing how to synchronize a directory with files from the Peregrine ''/data'', available under ''/mnt/pg-data'' on the login nodes to the new ''/projects'' on Hábrók:
+Normally, checking the server hostkey ensures that you are not inadvertently connecting to a system posing as Hábrók (known as a man-in-the-middle attack) by warning you that you are actually connecting to another machine. You can safely ignore this check at if the key for the host you are connecting to is listed in [[habrok:additional_information:hostkey_fingerprints|]].
-<code>
-rsync -av /mnt/pg-data/p123456/important_data/ /projects/p123456/important_data/
-</code>
-Note the slashes at the end of the source and the destination. The following flags have been used:
-  * ''-a'': archive to copy everything recursively including file ownership and permissions
-  * ''-v'': verbose to show the progress
-You can also enable compression using ''-z'', but this will only speed up the transfer of highly compressible data. Since sufficient bandwidth should be available for the transfers compression will probably only add overhead.
-The best thing about using ''rsync'' is that you can restart the transfer in case of failures, and ''rsync'' will just continue where it stopped.
+=== MobaXterm ===
-==== How do I migrate data from a group folder to Habrok? ====
+When reconnecting you will see a pop up window. Simply press "**Accept the new server hostkey and carry on connecting**"
-The group folders will also be available at ''/mnt/pg_data/pg-group'', and we are currently creating new groups on Habrok. These groups will have a similar naming pattern as on Peregrine, e.g. ''pg-group'' becomes ''hb-group''. We will then add the users to these new groups, and the new group will be the owner of the folder ''/mnt/pg_data/pg-group''. From this point, the data can be copied over to Habrok using ''rsync'', as explained above. The location for the group folder on Habrok will be ''/projects/hb-group''.
+{{:habrok:additional_information:remote_server_id_changed.png?400|}}
-==== How do I solve an error about the processor or OS not supporting certain instructions ====
+=== ssh connections on a terminal ===
-**Short answer**: ensure you compile your program on the same CPU architecture as the compute node you will then run it on.
+You will see a message with:
-You may run across an error when you try to run an application that tells you the operating system or processor does not support certain instructions. This is often accompanied by a list of acronyms which correspond to the instructions. This is an example error message:
 <code>
-Please verify that both the operating system and the processor support Intel(R) X87, CMOV, MMX, FXSAVE, SSE, SSE2, SSE3, SSSE3, SSE4_1, SSE4_2, MOVBE, POPCNT, AVX, F16C, FMA, BMI, LZCNT, AVX2, AVX512F, AVX512DQ, ADX, AVX512CD, AVX512BW and AVX512VL instructions.
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
+Someone could be eavesdropping on you right now (man-in-the-middle attack)!
+It is also possible that a host key has just been changed.
+The fingerprint for the ED25519 key sent by the remote host is
+SHA256:LnOMDB7/5L0OKJojsXb2CovSUGvd2k0U0oJ8L3xR2HI.
+Please contact your system administrator.
+Add correct host key in /home/user/.ssh/known_hosts to get rid of this message.
+Offending ED25519 key in /home/user/.ssh/known_hosts:13
+  remove with:
+  ssh-keygen -f "/home/user/.ssh/known_hosts" -R "login1.hb.hpc.rug.nl"
+Host key for login1.hb.hpc.rug.nl has changed and you have requested strict checking.
+Host key verification failed.
 </code>
-This happens because your program was compiled in a system that supports these instructions, but is running in a system that doesn't. Most likely you may have compiled your program on a different node than the one you are running your program from.
+Follow the instructions on the message and run:
-To get around this, you can make sure you compile your program in the same system that it will run. For example: if you need to run your program on one of the ''himem'' nodes, then you can submit a job that compiles your program, and subsequent jobs that then use the resulting executables to run your program. Alternatively, you can start an interactive session on a node with the target CPU architecture and compile your code interactively there. For example, assuming you want to compile your program for the ''himem'' nodes you could do ''srun --time=01:00:00 --partition=himem --pty /bin/bash''. This will queue an interactive session lasting up to one hour on which you can compile your code.
+<code>
+ssh-keygen -f "/home/user/.ssh/known_hosts" -R "login1.hb.hpc.rug.nl"
+</code>
+**Note that your command may be different, as the path to the ''known_hosts'' file is likely different in your situation**. The suggestion in the warning message should give you the correct path.