Mirroring
Mirroring is a strategy that pairs a primary chunk of one defined dbspace, blobspace, or sbspace with an equal-sized mirror chunk.
Every
write to the primary chunk is automatically accompanied by an identical
write to the mirror chunk. This concept is illustrated in the following
figure. If a failure occurs on the primary chunk, mirroring enables
you to read from and write to the mirror chunk until you can recover
the primary chunk, all without interrupting user access to data.
Figure 1. Writing data to both
the primary chunk and the mirror chunk
Mirroring is not supported on disks that are managed over a network. The same database server instance must manage all the chunks of a mirrored set.