Frequently asked questions

If you have a question that is not answered in the user guide, or need general help with a Research Computing system, please contact us at rc-help@colorado.edu. Some of our most frequently asked questions are presented here, with references to the user guide where more information can be found.

Remote access and logging in

How do I get an account?

Please email rc-help@colorado.edu for allocation request or management questions during this transition to Summit.

External users must first obtain a sponsored affiliate account with CU.

How do I register a one-time password (OTP) authenticator?

Register your authenticator at otp.colorado.edu. The process is documented in the user guide.

How do I log into my account?

Computational access to Research Computing systems is primarily provided via ssh. Access to storage resources is primarily provided via SSH and Globus.

Allocations

How do I get an allocation?

All new accounts are eligible for a start-up allocation upon request. Additional allocations are granted upon request with sufficient justification. More information is available in the user guide.

Batch queueing and job scheduling

What queues are available?

Research Computing uses Slurm, which uses a single job queue. In stead of queues, Slurm uses resource partitions and quality-of-service (QOS) values to set limits and priorities and to assign jobs to resources.

More information on selecting a QOS value for your job is available in the user guide.

How can I run multiple serial jobs in parallel?

Research Computing provides a simple load-balancer that can run multiple serial processes as tasks in a larger job.

When will my job start running?

Slurm can provide an estimate of when your jobs will start, along with what resources it expects to dispatch your jobs to.

$ squeue --user=$USER --start

Start times vary, and are largely dependent on the existing job load. A small debug job should start within a few minutes. A production 96-core job might take a few hours to start. A large, long job may spend several days or a week in the queue before starting.

More information is available in the user guide.

Storage

How long are backups saved in the PetaLibrary?

The PetaLibrary does not offer a conventional backup service. Storage options with "replication" or "second copy on tape" are designed to protect against a media failure, not accidental deletion. Changes to files on primary storage propagate automatically to the replicated copy, and if a file is deleted from the main storage it should not be expected to remain on the copy.

Can I mount my PetaLibrary project directory to my desktop computer?

We do not currently support NFS or CIFS exports from the PetaLibrary to the campus network, but similar (unsupported) access could be provided using sshfs.

How long does it take to access a file in the PetaLibrary Archive?

Files that have been migrated to tape can takes up to a minute to load the appropriate tape cartridge, plus another minute or two to advance the tape to the spot where the file is located. Data is then read from the tape at up to 160 MB/s. If all tape drives are in use by other file operations, processes, then the data recall will wait until a tape drive becomes available.

What tools and processes are available on the PetaLibrary for data and metadata management, curation, and information lifecycle management?

The PetaLibrary is designed primarily as a storage facility, leaving management of the stored data to the project owner. However, CU Research Data Services can offer assistance with many aspects of the data management process.

Can I back up my PC to the PetaLibrary?

The PetaLibrary has been funded to store research data, not for general-purpose storage or backups. The UCB Files storage service is an alternative for general file storage.

Why shouldn’t I use rsync to synchronize my local data with PetaLibrary Archive?

rsync synchronizes data by comparing file content in addition to file metadata. In an HSM environment like PetaLibrary Archive, these content comparisons require that all files be recalled from tape to disk, making rsync an inefficient mechanism for synchronizing files.

Why are my PetaLibrary transfers slow?

The PetaLibrary has a 10 Gb/s connection to the CU Science Network, allowing transfers at speeds up to 800 MB/s; but slower networks in your department or institution are likely to be the greatest limiting factor when moving data in and out of the PetaLibrary. If you have confirmed with your local network administration that you have a 10 Gb/s or faster connection between yourself and the PetaLibrary, contact us at rc-help@colorado.edu for help troubleshooting the connection.

Software

Will you install software for me?

We prefer that software is installed first by a user that will use it. For more information is available in the user guide.

How can I profile my code?

We recommend using the HPCToolkit.

How do I access LAPACK and BLAS?

We recommend using Intel's Math Kernel Library (MKL), especially if you are compiling with the Intel Compiler Suite.

$ module load intel/intel-13.0.0

If you prefer an open source implementation, we provide the GNU Scientific Library.

$ module load gsl/gsl-1.15_gcc-4.7.2