How to rebalance tables after new storage location was added to each of existing nodes?

I_MI_M Registered User

What's the best way (must be safe and hopefully reasonably fast) to rebalance existing tables given that:

  • there are 20+ nodes connected with 2x10GbE
  • each node initially had 2 10TB DATA,TEMP storage locations which are now very full
  • each node just had 3rd 10TB DATA,TEMP storage locations added which is basically empty
  • some projections are very large (>400GB/node)
    Number of nodes didn't change and isn't expected to change soon.
    Any suggestions on how to do it optimally would be appreciated.

Comments

  • Jim_KnicelyJim_Knicely Employee, Registered User, VerticaExpert

    Hi,

    Typically you'd rebalance a cluster after one of the following operations:

    • Change the size of the cluster by adding or removing nodes.
    • Mark one or more nodes as ephemeral in preparation of removing them from the cluster.
    • Change the scaling factor of an elastic cluster, which determines the number of storage containers used to store a projection across the database.
    • Set the control node size or realign control nodes on a large cluster layout.
    • Specify more than 120 nodes in your initial Vertica cluster configuration.
    • Modify a fault group by adding or removing nodes.

    You haven't done any of those, right?

    So is the question how to distribute the data to the new location?

    Check out the "Moving Data Storage Locations" doc page:

    https://my.vertica.com/docs/9.1.x/HTML/index.htm#Authoring/AdministratorsGuide/StorageLocations/MovingDataStorageLocations.htm

  • I_MI_M Registered User

    Creating and applying storage policy mostly worked (thanks!) However :
    1) it took extremely long time (20+ hours for a schema that's using 75TB of disk space); is there any way to reduce - or at least estimate - time that table or schema rebalancing will take
    2) free disk space after rebalancing is finished remain highly uneven between 3 storage locations - newly added (and initially free) storage location now has almost no free space left (20-25% free) and 2 existing ones have much more free disk space (40-55% free). Is there some way to achieve more even rebalancing?
    Vertica version is 8.1.1-11 - will upgrade to 8.1.1-(latest) help for future rebalancing operations?

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