HAMMER, and lots of it

I have a number of HAMMER-related news items, so I’ll break out the bullet points:

  • We have a detailed explanation of how HAMMER’s pruning system will work – follow the thread for more details and ideas.
  • Matthew Dillon is trying HAMMER for his backup system. His original UFS system used hardlinks to keep all the backups together; the inodes used would be more than fsck could handle with that system’s RAM. HAMMER doesn’t need those hardlinks because of the snapshot ability, and completes the backup process much faster.
  • There’s also blogbench numbers comparing UFS and HAMMER; strangely, UFS sees a performance degradation when using a large number of files when HAMMER does not. This may mean a real speed advantage or a testing anomaly; it certainly deserves investigation.