Server I/O when the GAD status is Mirrored
When the GAD status is Mirrored, the I/O mode of the P-VOL and S-VOL is
Mirror (RL). As shown in the following figure, a write request sent to a GAD
volume is written to both pair volumes, and then a write-completed response
is returned to the host.
Read requests are read from the volume connected to the server and then
sent to the server. There is no communication between the primary and
secondary storage systems.
Related topics
• Monitoring GAD status on page 1-10
• Global-active device and server I/O on page 1-14
Server I/O when the GAD status is Mirroring
When the GAD status is Mirroring, the I/O mode for the P-VOL is Mirror (RL),
and the I/O mode for the S-VOL is Block.
Write requests are written to both pair volumes, and then the write-
completed response is returned to the server. Because the S-VOL's I/O mode
is Block, it does not accept I/O from the server, but the data written to the P-
VOL is also written to the S-VOL by the primary system, as shown in the
following figure.
Overview of global-active device
1-15
Hitachi Virtual Storage Platform G1000 Global-Active Device User Guide
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