Minutes 2025-01-16

RAID (and ZFS) By: Noah

• RAID stands for “Redundant Array of [Inexpensive/Independent] Disks”
• Used by enterprises for high availability on drives and resiliency.

Drawbacks over flat Disks

• increased power draw

RAID levels

• RAID0
  • Storage is that of every disk combined
  • Fastest for reading and writing
  • not really used anymore
• RAID1
  • One disk replicated across every other disk
  • Common for boot drives
• RAID5
  • Any one disk is allowed to fail in a given array without losing any data
  • used to be a gold standard, but fell out of favor due to disk size increasing
• RAID6
  • Any two disks can fail in a given array without losing data
  • the new gold standard
  • if disks fail during rebuild, it allows another to fail.

Nested RAID levels

• RAID10
  • RAID01 (bad)
  • WMTU uses RAID60

Weird RAID levels

• RAID2
  • implemented own error correction
  • no reason to use it at all because HDDS implements its own error correction
• RAID3
  • Striped data at byte-level rather than block levels
  • Replaced by RAID5
  • used in video streaming

ZFS

• zfs is the storage administrator, while the user only has to check in
• arrays are now pools
• logical volumes are now datasets
• has its own approach to logical structure
• calls RAIDs something different RAID0 -> stripe
• Described as paranoid because it doesn’t trust anything from your disks and constantly checks and compares information to parity calculation.
• Shell server is set with ZFS in RAID10 all in one single zpool, which allows the shell to put a quota on datasets, so no users can get out of hand
• Extra features
  • has a cache vdev that reads in a ring buffer
  • SLOG, stores the ZFS intent
• biggest issue: licensing
  • Sun was trying to get out of the GPL and then have parasite companies from directly shipping ZFS
  • now oracle has ZFS and has first-party support on Solaris
  • maintains BTRFS support
• OpenZFS
  • last open-source version of ZFS
  • Under MIT license
  • used to be better supported on the BSD’s
• BTFRS
  • made a few advancements in filesystems since ZFS
  • Great for home labs
  • biggest problem: no RAID5/6, might not ever be supported
  • Better Linux integration, don’t have to worry about importing kernel modules
• CEPH
  • Different take on filesystems
  • only 6-9 servers with CEPH under LUG jurisdiction
  • Treats all disks in the cluster as one giant group
  • Overkill for our purposes
  • the cluster self-manages
  • common for VM images
  • can pick and choose the redundancy per file

LUG News

• Cypher-Con is happening soon
  • Not gonna be reimbursed by RED TEAM or college
  • happening in Milwaukee
  • provided two free hotel rooms
• Got a subnet from IT
  • Total of 30-ish public addresses
  • can use it to reverse-net for people who don’t have their own public IP addresses
  • potential Zigbee talk
  • hosting an access control booth to do OSDP challenges
• Tunnel Bob
  • Some random guy keeps breaking into the University of Wisconsin, Madison tunnels
    • Cops have chased him through the tunnels and have yet to apprehend him
    • Guys at MIT did similar in the 80's, mapping out steam tunnels (vadding/tunneling)
      • 'vadding' mentioned in the jargon file on most systems, that's where it comes from
        • Mentions "elevator rodeo"
          • "Watch out for elevator counterweights"
• Idea for making cards that are LUG-themed
• Trying to get the equipment for LUG shirts