[Moosefs-users] Question about MooseFS metadata distribution/recovery

[René P. <ly...@lu...>]

Hello!

We have the following scenario with a MooseFS deployment.

- 3 servers
  - server #3 : 1 master
  - server #2 : chunk server
  - server #1 : chunk server, one metalogger process running on this node

Server #3 suffered from a hardware RAID failure including a trashed JFS
file system where the master logs were on. We tried

- recovering the log/state data from server #1 and restarting the master
  process, and
- using the data from the metalogger process and starting a new master on
  server #1 (including changing the configs to use the new master as
  described in the documentation).

The MooseFS mount is accessible, but some file operations involving data
end in processes hanging in the "D" state (uninterruptible sleep). Logs on
the chunk servers show that the MooseFS is missing data although the state
of the chunk servers have not changed (no reboot, no file system damage,
only reconfigured master).

Is there a way to extract the data from the chunk directories?
Is the a "fsck.mfs" or a similar tool? mfsfilerepair is not useful, because
it only zeroed a file which was affected by the "D" state problem.

We're currently trying to recover the original master's directory
containing the meta data. Is there any documentation regarding the meta
data or chunk data besides the source code? Does someone experienced a
similar situation?

Best regards,
René Pfeiffer.

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