Fringing Host (test cluster only)


In addition to the normal correlation work, some other analytical work is done. At the USNO, they have two fringing boxes which are connected to but separate from the correlator. Since the test cluster is also tasked with being a backup correlator it was decided to replicate a fringing box at the AOC. A compute node from the old correlator (node-004) was repurposed to become fringe-1. Fringe-1 lives on the admin subnet and provide NFS mounts to allow interaction with the correlator, etc.


The host has two 1TB 2.5" hard disks. One disk serves as a system disk and has RHEL 7.9 (12/7/20) installed; the 1TB capacity is overkill but it's cheap to get more disk. The second disk contains a single partition and is mounted as /export. The intent is that the second disk will server primarily as an area to hold whatever data is useful to the backup operation.


Fringe-1 uses two NICs. On the correlator admin net it lives at and uses a static IP address. On a second NIC, fringe-1 sits on an NRAO subnet using a reserved IP address. The IP address is and the NRAO DNS name is usno-fringe-1-ext. The NRAO name and IP address will make it easier for USNO personnel to log into the NRAO network using IT-provided accounts and then reach the fringer.


The correlator maintains its own set of accounts. These should match up with those on the USNO cluster to maintain sysadmin and user sanity. Thus these accounts will not likely match up with the accounts used to log into the NRAO network.

Cluster accounts do not support password access but use certificates instead. When an NRAO account is created for a USNO member, they will need to create a certificate on that account and then provide the public key to a cluster admin so that it may be installed in the appropriate ~/.ssh/authorized_keys file.

Normal operation will be performed via the oper account. This account has limited privileges. A small number of USNO personnel will use individual accounts and will be able to use sudo (via the wheel group) to selectively accomplish tasks which require privileges.

-- JimJacobs - 2020-12-08
Topic revision: r3 - 2022-07-20, MarkWainright
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