Table of contents

• Same Slurm instance, different architectures
• Alpha x86 vs Grace CPU arm64
• Why users still need separate software layouts
• Why subdirectories matter
• Python and package management guidance
• Compiled software and library issues
• Containers in a mixed-architecture environment
• Recommended directory layout
• Best practices

Same Slurm instance, different architectures

It is completely reasonable for x86 and arm64 systems to exist under the same Slurm control plane. From the user perspective, that means the queueing system may feel unified even though the execution environments are not interchangeable.

• You may submit jobs through one Slurm environment and still target very different CPU architectures.
• The scheduler can be shared while the runtime software stacks remain architecture-specific.
• Users need to keep track of which partition, node type, or feature corresponds to which architecture.

Key point: a shared Slurm instance does not mean a shared binary interface. Jobs may be scheduled through the same system while still requiring different software builds underneath.

Alpha x86 vs Grace CPU arm64

For users, the main distinction is that Alpha should be treated as the x86 environment, while Grace CPU systems should be treated as arm64 environments built on Grace-Grace nodes. Even if your project directory is shared across both, the installed software and compiled outputs should not be assumed to carry over cleanly.

In other words, the source tree can often be the same, but the executable products are not. That distinction is the most important idea for users to keep in mind.

Why users still need separate software layouts

The most common mistake in a mixed-architecture environment is assuming that a shared filesystem should also imply a shared environment directory. That works for source code and data, but it usually breaks for anything that gets installed, cached, compiled, or linked.

• Python wheels built on Alpha x86 may not import on Grace CPU systems.
• Compiled binaries and shared objects are architecture-specific.
• Build caches can silently mix incompatible outputs if you reuse the same directory names on both architectures.

Simple rule: share source code and data, but separate environments, builds, installs, and caches by architecture.

Why subdirectories matter

Architecture-specific subdirectories make it obvious which files belong to Alpha x86 and which belong to Grace CPU arm64. They also prevent one architecture from overwriting another architecture's environment or build artifacts.

project/
  src/
  data/
  envs/
    alpha-x86/
    grace-arm64/
  build/
    alpha-x86/
    grace-arm64/
  install/
    alpha-x86/
    grace-arm64/
  wheels/
    alpha-x86/
    grace-arm64/
  logs/
    alpha-x86/
    grace-arm64/

You can use other naming conventions if you prefer, but the architecture distinction should be visible in the path itself.

Python and package management guidance

• Create separate Python virtual environments for Alpha x86 and Grace CPU arm64.
• Do not point both architectures at the same virtual environment directory or install prefix.
• Use architecture-labeled virtual environment names and paths.
• Be careful with wheel caches, compiled extensions, and pip build artifacts on shared filesystems.

# Example layout with Python virtual environments
python3 -m venv /project/myproj/envs/alpha-x86/py311
python3 -m venv /project/myproj/envs/grace-arm64/py311

# Activate the environment for the current architecture
source /project/myproj/envs/alpha-x86/py311/bin/activate
# or
source /project/myproj/envs/grace-arm64/py311/bin/activate

# Useful checks
uname -m
python -c "import platform; print(platform.machine())"

Compiled software and library issues

Most portability problems show up in compiled layers rather than in pure Python code. This is where users should expect the strongest distinction between Alpha x86 and Grace CPU arm64.

• CPU-specific headers and intrinsics: x86 oriented code paths may require conditional compilation or alternate implementations on arm64.
• Compiler flags: flags that make sense for x86_64 may be invalid or suboptimal on arm64.
• Inline assembly: architecture specific assembly almost never carries across directly.
• Older configure logic: some packages need updates to recognize aarch64 correctly.
• Prebuilt vendor libraries: some artifacts may exist only for one architecture, forcing a rebuild or alternate dependency choice.

# Helpful diagnostics
file /path/to/binary
ldd /path/to/binary
readelf -h /path/to/binary | head

Containers in a mixed-architecture environment

Containers simplify dependency management, but they do not erase architecture boundaries. A container image built for x86_64 is still an x86_64 image, and an arm64 system still needs an arm64-compatible image.

• Publish separate tags or clearly labeled multi-arch images when both Alpha and Grace CPU systems are supported.
• Record the target architecture in the image tag, image name, or documentation.
• Keep the same mount structure across architectures when possible so job scripts stay readable.

# Example tag pattern
registry.example.org/myproj/train:alpha-x86
registry.example.org/myproj/train:grace-arm64

Recommended directory layout

$HOME/software/
  alpha-x86/
    bin/
    lib/
    include/
  grace-arm64/
    bin/
    lib/
    include/

/project/myproj/
  source/
  data/
  envs/
    alpha-x86/
    grace-arm64/
  build/
    alpha-x86/
    grace-arm64/
  install/
    alpha-x86/
    grace-arm64/

This layout makes it easy to share the project while still preserving a clean separation between x86 and arm64 artifacts.

Best practices

• Treat Alpha and Grace CPU as separate software targets: same Slurm instance does not mean same binary environment.
• Label everything clearly: use path names like alpha-x86 and grace-arm64.
• Compile natively when possible: build on the architecture you intend to run on.
• Check the architecture first when something fails: mismatched binaries can look like import, linker, or loader errors.
• Keep source shared but builds separate: this is the cleanest way to support both environments.
• Use architecture specific containers where practical: especially for complex dependency stacks.