zdaemon
zdaemon is a Unix (Unix, Linux, Mac OS X) Python program that wraps commands to make them behave as proper daemons. zdaemon provides a script, zdaemon, that can be used to run other programs as POSIX (Unix) daemons. (Of course, it is only usable on POSIX-complient systems.) Using zdaemon requires specifying a number of options, which can be given in a configuration file, or as command-line options. It also accepts commands teling it what to do. Start a process as a daemon. Stop a running daemon process. Stop and then restart a program. Find out if the program is running. Send a signal to the daemon process. Reopen the transcript log. Commands can be given on a command line, or can be given using an interactive interpreter. We can specify a program name and command-line options in the program command. Note, however, that the command-line parsing is pretty primitive.
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DRBD
DRBD® (Distributed Replicated Block Device) is an open source, software‑based, shared‑nothing block storage replication solution for Linux, designed primarily to deliver high-performance, high‑availability (HA) data services by mirroring local block devices between nodes in real time, either synchronously or asynchronously. Implemented deep in the Linux kernel as a virtual block‑device driver, DRBD ensures local read performance with efficient write‑through replication to peer(s). User‑space utilities like drbdadm, drbdsetup, and drbdmeta enable declarative configuration, metadata management, and administration across installations. Originally built for two‑node HA clusters, DRBD 9.x extends support to multi‑node replication and integration into software‑defined storage (SDS) systems such as LINSTOR, making it suitable for cloud‑native environments.
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distcc
Distcc is a distributed compilation system that accelerates C, C++, Objective-C, and Fortran builds by offloading compile jobs across multiple networked machines. It integrates seamlessly with GCC and Clang toolchains, transparently intercepting compiler calls and redistributing them to remote daemons while preserving optimization flags, include paths, and dependency tracking. Its client-server architecture features a lightweight listener that manages job queues, prioritizes local compilation when needed, and automatically detects available hosts via simple configuration or DNS. Distcc supports cross-compilation environments, SSH tunneling for secure clusters, blacklisting of unreliable servers, and integration with build systems like Make, CMake and Ninja. Monitoring tools provide real-time statistics on job distribution and throughput, and compatibility with compilation databases (compdb) enables granular control over distributed workloads.
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Apache Helix
Apache Helix is a generic cluster management framework used for the automatic management of partitioned, replicated and distributed resources hosted on a cluster of nodes. Helix automates reassignment of resources in the face of node failure and recovery, cluster expansion, and reconfiguration. To understand Helix, you first need to understand cluster management. A distributed system typically runs on multiple nodes for the following reasons: scalability, fault tolerance, load balancing. Each node performs one or more of the primary functions of the cluster, such as storing and serving data, producing and consuming data streams, and so on. Once configured for your system, Helix acts as the global brain for the system. It is designed to make decisions that cannot be made in isolation. While it is possible to integrate these functions into the distributed system, it complicates the code.
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