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--- guide:connect [2018/04/18 14:05]
thlatshwayo [Blocked IP's]
+++ guide:connect [2026/06/18 19:45] (current)
ccrosby [Connecting to the CHPC]
@@ Line 2: / Line 2: @@
 The CHPC hosts a supercomputer comprising:
-    * 1008 regular compute nodes with 24 cores and 128 GiB of RAM each; and
+    * 1008 regular compute nodes with 24 cores and 128 GiB of RAM each;
-    * 5 large memory nodes with 56 cores 1TiB of RAM each
+    * 360 regular computes nodes with 24 cores and 64 GiB of RAM each;
+    * 4 large memory nodes with 56 cores and 1TiB of RAM each;
+    * 9 [[guide:gpu|GPU]] nodes.
-The cluster will be augmented in the future with:
-  * a GPU-powered visualisation node; and
-  * other specialised servers
 =====Host Name=====
@@ Line 21: / Line 20: @@
 where //**''username''**// is replaced by the user name assigned to //your// account at the CHPC.
+===== Dedicated scp.chpc.ac.za =====
+A dedicated node, ''**scp.chpc.ac.za**'' is available for scp file transfers:
+<code>
+  scp src.tar.gz username@scp.chpc.ac.za:~/lustre/
+</code>
 ===== Transferring Files =====
-Use scp or sftp to transfer files to or from your home directory on the CHPC systems.  For example
+**Large data sets should be transferred by means of [[howto:globus|Globus]].  Globus is faster and more reliable than scp.**
+You can also use scp or sftp to transfer files to or from your home directory on the CHPC systems.  For example
 <code>
-  scp src.tar.gz username@scp.chpc.ac.za:~/scratch/
+  scp src.tar.gz username@scp.chpc.ac.za:~/lustre/
 </code>
-to copy the file //src.tar.gz// to your scratch directory on the CHPC cluster.  If you would like a more user-friendly method, consider [[https://filezilla-project.org|FileZilla]]
+to copy the file //src.tar.gz// to your lustre directory on the CHPC cluster.  **Please do not transfer files directly to lengau.chpc.ac.za.** It is a shared login node, and in order not to overload it, file transfer should be done to the dedicated scp server. Please note that storage space in your home directory is very limited.  Large amounts of data should rather be transferred to your storage space on the lustre file system.  For a ** typical ** user, there will be a symbolic link to the user's directory on lustre, hence the ~/lustre/ target.  Alternatively, you may wish to copy directly to your lustre storage, in which case you could do the following:
+<code>
+  scp src.tar.gz username@scp.chpc.ac.za:/mnt/lustre/users/username/
+</code>
+If you would like a more user-friendly method, consider [[https://filezilla-project.org|FileZilla]]
 **Note:** use ''scp.chpc.ac.za'' as the server when transferring files.
-===== Dedicated scp.chpc.ac.za =====
-A dedicated node, ''**scp.chpc.ac.za**'' will become available for large or long-running transfers:
-<code>
-  scp src.tar.gz username@scp.chpc.ac.za:~/scratch/
-</code>
 =====Recommended: ssh keys =====
@@ Line 64: / Line 74: @@
 </code>
 And the next time you ssh or scp to the CHPC login node you won't have to use your password!
+====NOTE: ssh FILE PERMISSIONS====
 Notice that you need to change the permissions of the //.ssh// directory and the //authorized_keys//
 file on the login nodes to make them private and readable by you only before ssh will use the new public key.
+<code>
+chmod -R g-rwx,o-rwx ~/.ssh
+</code>
+**You also need to make sure your home directory does not have write ''w'' enabled for group and other fields.**
+<code>
+ls -ld ~
+drwxr-xr-x 19 user user 4096 Aug 15 12:01 /home/user
+</code>
+which is done with
+<code>
+chmod 0750 ~
+</code>
+to make your entire home directory private; or
+<code>
+chmod 0755 ~
+</code>
+to allow other users to view your files.
+====ssh error: REMOTE HOST IDENTIFICATION HAS CHANGED!====
+This error occurs if the keys used by the host are different from that used last time you connected to it.
+You can use
+  ssh-keygen -R badhost
+to remove all keys associated with the host //badhost// from your ''known_hosts'' file.
+This is safe to do because the new host key entry will be added back in next time you ssh in.
+If you want to look at or edit the ''.ssh/known_hosts'' file, it is located in the ''.ssh'' sub-directory within your home directory on the //Lengau// cluster.
+For example, after logging in:
+<code bash>
+cd .ssh/
+ls
+authorized_keys  id_ecdsa  id_ecdsa.pub  known_hosts
+</code>
+Once you have changed into the ''.ssh'' sub-directory you can then use an editor (e.g. ''nano known_hosts'') to edit the file and delete the bad line.
 ===== Connecting from MS Windows =====

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