Disclaimer: This project is not maintained anymore

Halon

Halon is a fault tolerant, resilient system for maintaining a globally consistent view of large clusters and automatically repairing them in real-time as faults arise.

NOTE

Please note that this code was originally developed for the CORTX project but it has been deprecated and is no longer currently used. However, it is publicly available for historical interest as well as any other reasons that someone might be interested. All interested parties are encouraged to try to use this software for whatever purpose that might be of benefit to them.

Building from sources

Prerequisites:

sudo yum install leveldb-devel libgenders-devel

# Install the Haskell Tool Stack
curl -sSL https://get.haskellstack.org/ | sh

Build Mero first

(cd /path/to/mero && scripts/m0 make)

then build Halon

M0_SRC_DIR=/path/to/mero scripts/h0 make

Building and installing rpm packages

( cd /path/to/mero &&
  make rpms-notests &&
  sudo yum install ~/rpmbuild/RPMS/x86_64/mero*.rpm )
make rpms
sudo yum install ~/rpmbuild/RPMS/x86_64/halon*.rpm

Documentation

The full documentation for Halon is kept in the doc/ directory. To build the documentation and view it in your browser:

cd doc
stack exec make html

You can also generate PDF's for each document in the set, as well as the man pages for user commands:

stack exec make latexpdf
stack exec make man

Running tests

Unit tests:

scripts/h0 test

System tests:

scripts/h0 run-st

Starting/stopping the cluster

Single-node cluster:

# Install Mero and Halon systemd services; start halond-s;
# generate facts file.
scripts/h0 init

# Bootstrap the cluster.
hctl mero bootstrap

# Wait for all cluster processes to come online.
hctl mero status
sleep 90  # Zzz...
hctl mero status

# Stop the cluster.
hctl mero stop

# Stop halond-s; erase cluster data, metadata and generated configuration;
# uninstall systemd services.
scripts/h0 fini

Multi-node cluster:

# Prepare cluster configuration file.
cat >/data/cluster.yaml <<EOF
confds: [ cmu.local ]
ssus:
  - host:  ssu1.local
    disks: /dev/sd[b-g]
  - host:  ssu2.local
    disks: /dev/sd[b-g]
clovis-apps: [ client1.local ]
EOF

# Install Mero and Halon systemd services; start halond-s;
# generate facts file.
M0_CLUSTER=/data/cluster.yaml scripts/h0 init

# Bootstrap the cluster.
hctl mero bootstrap

# Wait for all cluster processes to come online.
hctl mero status
sleep 90  # Zzz...
hctl mero status

# Stop the cluster.
hctl mero stop

# Stop halond-s; erase cluster data, metadata and generated configuration;
# uninstall systemd services.
M0_CLUSTER=/data/cluster.yaml scripts/h0 fini

Caveats

By default, halonctl attempts to listen on the local hostname. This will fail if there is not an entry for the FQDN in /etc/hosts. In this case, you can either add such an entry or use the -l option to specify an alternate listen address.

Also by default, Halon attempts to verify that it is running against the same version of the Mero library that it was built with. This check can prevent unexpected bugs, but may occasionally inhibit testing. You can disable this check by setting the DISABLE_MERO_COMPAT_CHECK environment variable.

System requirements

Architecture: amd64, x86.

OS requrements: geneneric linux distribution In case of mero build: Linux distribution should be supported by mero. System libraries: leveldb, libgmp, libffi, rabbitmq-c.

Memory requirements: 0.5Gb - singlenode setup. 2Gb - 6 nodes cluster.