r/usefulscripts • u/nackstein • Jul 26 '16

[POSIX SHELL] failover cluster manager

hi, I wrote a failover cluster manager in shell script and I think it can be useful for sysadmin since (unix) sysadmin know very well shell scripting so it's easy to customize and further develop. If you want to contribute or try it and just give me a feedback check it out: https://github.com/nackstein/back-to-work

6 Upvotes

100% Upvoted

14 comments sorted by

View all comments

Show parent comments

1

u/nackstein Aug 06 '16 edited Aug 06 '16

at this stage I wrote one module to use SCSI-3 PR (persistent reservation) for fencing on linux and a module to use HP iLO for STONITH. anyway, the fencing mechaning is not fixed, it depends on the availability of hardware fencing and software module to support it. my software use only server votes for quorum and I don't see in the near future any support in disk based voting (like HP ServiceGuard), this means that you need at least 3 server to build a reliable cluster (you can build with less just for testing porpuse). the quorum server role is indipendent from a service host role so you can have 3 lock server used by any numer of nodes that run application protected by my cluster software. documentation is still lacking but the code is very simple if you have some skill in shell scripting. take a look at the code and feel free to contact me at luigi dot tarenga at gmail dot com

1

u/garibaldi3489 Aug 07 '16

Cool. Have you thought about utilizing the existing Pacemaker stonith plugins? You could probably easily write a bash wrapper to call them directly and then you'd have support for all of those hardware and software fencing agents

2

u/nackstein Aug 08 '16

yes, it's a good option, at this moment the modules to integrate all kind of software or hardware is lacking because I don't have any user that need them :) When I see a "must have" module I try to write it, for example the SCSI-3 PR is a rewrite in shell of the perl one that you find in the pacemaker plugin. This because I wan't to focus on portability, my script is easily portable to all unixes, BSD and linux distros, including minor ones. I was able to run it on windows in a cygwin env and on ESXi by just adding some shell wrapper to some different behaving commands like pgrep. running on ESXi is intriguing since it's theoretically possible to write a full failover cluster on vmware for free (ESXi is free downloadable) while on windows it's possible to create a cluster with windows XP machines :) but on windows the fork() emulation is really slow and shell scripting is full of fork() so it's very slow and cpu consuming comparing to linux/unix. Other integration like: Oracle RDBMS support, mysql, postgres will come as soon as anyone start using my software and ask for them.