Zstash HPSS Archive

Zstash – HPSS long-term archiving solution for E3SM

Zstash is written in Python 3 using standard libraries. Its design is intentionally minimalistic to provide an effective long-term HPSS archiving solution without creating an overly complicated (and hard to maintain) tool.

Key features:

• Files are archived into standard tar files with a user-specified maximum size optimized for HPSS storage, typically 128 to 256 GB.
• Tar files are created locally first, then transferred to HPSS. If no HPSS is available or the user specifies to not use HPSS, these files will instead be archived locally.
• Checksums (md5) of input files are computed on-the-fly during archiving. For large files, this saves a considerable amount of time compared to separate checksumming and archiving steps. (Checksums are computed on-the-fly again when extracting files to verify file integrity.)
• Checksums and additional metadata (size, modification time, tar file and offset) are stored in an SQLite3 index database.
• The SQLite3 database enables faster retrieval of individual files by providing the containing tar file and offset (location) within that tar file.
• Parallel extraction is supported for additional performance.