[Moosefs-users] Serious bug in "mfsmetarestore" when using snapshots

[Michal B. <mic...@ge...>]

Hi!

 

We recently found a serious bug in MooseFS - when using "mfsmakesnapshot" it
appears that "mfsmetarestore" fails to properly restore the metadata. 

 

For the moment we present an easy method to avoid this error. While
restoring the metadata in the first step you need to pass
"metadata.mfs.back" in "mfsmetarestore" - without the changelogs. In the
second step you pass to the "mfsmetarestore" the newly created file along
with the changelogs. 

 

So instead of: 

"mfsmetarestore -a -d /usr/local/var/mfs" 

 

you need to do the following steps: 

1. "mfsmetarestore -m /usr/local/var/mfs/metadata.mfs.back -o
/usr/local/var/mfs/metadata.mfs.backback"

2. "mv /usr/local/var/mfs/metadata.mfs.backback
/usr/local/var/mfs/metadata.mfs.back"

3. "mfsmetarestore -a -d /usr/local/var/mfs"

 

In case of restoring the metada from metalogger you need to use
"metadata_ml.mfs.back" instead of "metadata.mfs.back".

 

This error is present in all versions of MooseFS (exactly from the moment
when SNAPSHOT operation has been introduced). So, if you have "SNAPSHOT" in
your changelogs you need to use the above steps when restoring the metadata.
The bug will be fixed in the next release.

 

 

Kind regards

Michał Borychowski 

MooseFS Support Manager

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Gemius S.A.

ul. Wołoska 7, 02-672 Warszawa

Budynek MARS, klatka D

Tel.: +4822 874-41-00

Fax : +4822 874-41-01