The migration utility is built inside the system as part of nodes startup 
sequence and is available in the current master. When a storage version that 
requires migration is detected on the node startup, it will be automatically 
triggered.
As for the backup, taking a copy of each configured storage directory as well 
as the transaction logs directory in any format, compressed or uncompressed, 
should be sufficient. In case of any failure during the migration, using the 
old binaries with the backup copy should work.

Cheers,
Murtadha

On 11/29/2017, 12:44 AM, "Michael Carey" <[email protected]> wrote:

    Murtadha,
    
    When the utility is ready, could you post another note on where it lives 
    and how to use it and also what the best practice advice is on how to 
    back up before proceeding?  Thx!
    
    Cheers,
    
    Mike
    
    
    On 11/27/17 3:07 PM, Murtadha Hubail wrote:
    >
    > Hi all,
    >
    > Recently, a feature was added to AsterixDB to allow a dataset to be 
    > rebalanced from a set of nodes (a node group) to another node group. 
    > Rebalancing a dataset will result in redistributing the dataset’s data 
    > to the nodes in the new node group. Since a single node may appear in 
    > both the old and the new node group, a new level in the storage tree 
    > had to be introduced to distinguish between the old and the new copies 
    > of the dataset. To do that without breaking backward compatibility for 
    > existing users who would like to upgrade binaries without having to 
    > reload their existing data, we added a migration utility that will run 
    > on the node startup and migrate the data to the new storage structure. 
    > *_However, it is recommended that you backup your existing data to 
    > avoid any permanent data loss in case of any unexpected failures 
    > during the migration process_*_._
    >
    > Cheers,
    >
    > Murtadha
    >
    
    


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