Using mirroring

Mirroring starts when you create a mirror chunk for each primary chunk in a dbspace, blobspace, or sbspace.

When you create a mirror chunk, the database server copies data from the primary chunk to the mirror chunk. When this process is complete, the database server begins mirroring data. If the primary chunk contains logical-log files, the database server does not copy the data immediately after you create the mirror chunk but waits until you perform a level-0 backup. For an explanation of this behavior see Creation of a mirror chunk.
Important: You must always start mirroring for an entire dbspace, blobspace, or sbspace. The database server does not permit you to select particular chunks in a dbspace, blobspace, or sbspace to mirror. You must create mirror chunks for every chunk in the space.
You start mirroring a storage space when you perform the following operations:
  • Create a mirrored root dbspace during system initialization
  • Change the status of a dbspace from unmirrored to mirrored
  • Create a mirrored dbspace, blobspace, or sbspace

Each of these operations requires you to create mirror chunks for the existing chunks in the storage space.

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