How to recover master from a backup on moosefs-ce.2.0

Question

My mfs version is moosefs-ce-2.0, it is installed on debian6 which is ext3 filesystem. There are a master and a metalogger and some chunkserver, when my master is down. How to recover master from metalogger? The documentation moosefs.org provided is outdated, I can't find more detailed information on documentaton. Or how to config muti-master on moosefs-ce-2.0?

Answer 1

It is described in the documentation. You can find the documentation here: MooseFS Documentation. Paragraph 4.2 (page 19) of MooseFS User's Manual "Master metadata restore from metaloggers" says:

4.2 Master metadata restore from metaloggers

In MooseFS Community Edition basic configuration there can be only one master and several metaloggers. If for some reason you loose all metadata files and changelogs from master server you can use data from metalogger to restore your data. To start dealing with recovery first you need to transfer all data stored on metalogger in /var/lib/mfs to master metadata folder. Files on metalogger will have ml prefix prepended to the filenames. After all files are copied, you need to create metadata.mfs file from changelogs and metadata.mfs.back files. To do this we need to use the command mfsmaster -a. Mfsmaster starts to build new metadata file and starts mfsmaster process.