Update Text below in purple bold was updated on 7/3/23.

Update Text below in green bold was updated on 6/27/23.

Update Text in below in bold red was updated on 5/1/2023.

Update Text below in purple was updated on 4/6/2023.

Update Text below in green was updated on 3/1/2023.


Throughout 2023 LC will be transitioning its TOSS 3, x86_64 systems to the TOSS 4 operating system. This major operating system transition will effect most LC systems (see list below). Nearly all users of these systems will be impacted and will need to make modifications to their workflows.

Unlike typical TOSS upgrades, this transition involves building a new operating system and user environment from the ground up. For example, users will notice discontinued support for some software available on TOSS 3 and changed paths for much of the software that receives continued LC support. User-supported software and binaries will need to be re-built for TOSS 4. Most previously cross-compatible software will continue to work only on TOSS 3 systems, and software built on TOSS 4 will be compatible across TOSS 4 systems.

TOSS 4 is based on RHEL8. Any executable will likely have to be rebuilt to run on a TOSS 4 system.

  • The SYS_TYPE will be toss_4_x86_64_ib or toss_4_x86_64.
  • To support code portability with other HPC centers, LC is changing the way it packages compilers. Details on the how LC is now packaging and providing compliers is listed on our Compilers page.
  • Moab wrappers are no longer supported. The moab2slurm utility is available to convert Moab msub jobs scripts to the Slurm sbatch equivalents. (see the moab2slurm man page). See the Batch System Cross Reference Guide for the slurm equivalents of moab commands.
  • Due to security requirements, TOSS 4 only supports 4096-bit (or larger), RSA-type ssh keys. Users with DSA, EcDSA, and ED25519 type keys may have to generate a new key. Instructions for generating ssh keys can be found on the Accessing LC Systems page.
  • Due to system changes, users may get a "WARNING: POSSIBLE DNS SPOOFING DETECTED!" error message when connecting to a newly transitioned system. This can be resolved by downloading the LC public hosts file or contacting the hotline.
  • The /p/lscratchh symlink has been removed. Users must use the real path /p/lustre2. 
  • The /p/lscratchrza symlink has been removed. Users must use the real path /p/lustre1/
  • Several tools that were available under TOSS 3 are not currently available on TOSS 4 systems. Alternatives are documented here.

To prepare for this transition, users can request access to the Poodle system which is already at TOSS 4.

The initial schedule of transitions is: 

Transition Date Machine
2/14-15 Boraxo and Mammoth
2/21-22 Borax
2/21-23 Oslic and Pascal
4/18-4/20  Quartz
Cancelled† Sonar
4/18-4/20  RZslic
Cancelled† RZSonar
5/16-5/18 Ruby
5/30-6/1  RZTopaz, RZTrona
6/13-6/15 Agate, Vertex
6/20-6/22 Tron, CSonar
6/27-6/29 Cslic
7/11-7/15  Mica
7/11-7/15  Pinot (SNSI)
7/18-7/20  Magma
7/25-7/27 Jade
7/25-7/27  SCFVNC


†Sonar and RZSonar hardware will be replaced. New systems will run TOSS 4.