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

[René P. <ly...@lu...>]

Hello, Michał!

I have an update on the metadata case.

On Dec 14, 2011 at 0937 +0100, Michał Borychowski appeared and said:
> …
> This is still too little information about how we could help you... What
> about metaloggers? Don't you have metadata_ml.mfs.back and
> changelog_ml.*.mfs files? You could put them on ftp as tar.gz and give us
> a link so that we try to recover them.

I will take some time to compile this information, because the servers in
questions are managed by different teams (long story) and the coordination
did not run smoothly (i.e. the metalogger's logs might have been
overwritten, because the MooseFS was continued to be used after the master
server crash).

I searched through 129 GB of salvaged data from the master and found not a
single file with a metadata signature. 

> In "emergency" situations MooseFS tries to write metadata file on the
> master machine in these locations: … You can try to find them there, but
> as RAID went broken it is possible you won't see them.

Correct, we've not found any *emergency* files on the dump either.

Since the state of the MooseFS moved back in time to 28 June 2011 we
suspect that this is the time when the data corruption started, and since
no warnings or errors were logged by the servers or the hardware
controllers no one noticed.

Best,
René.

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