EMC VMAX 100K, Руководство по эксплуатации продукта

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The number of transmit cycles supported at the R1 side. Enginuity 5876 supports
only a single cycle. HYPERMAX OS supports multiple cycles queued to be
transferred.
SRDF sessions can be managed individually or as members of a group.
In asynchronous mode, I/Os are collected into delta sets. Data is processed using 4
cycle types that capture, transmit, receive and apply delta sets:
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Capture cycle—Incoming I/O is buffered in the capture cycle on the R1 side. The
host receives immediate acknowledgment.
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Transmit cycle—Data collected during the capture cycle is moved to the transmit
cycle on the R1 side.
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Receive cycle—Data is received on the R2 side.
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Apply cycle—Changed blocks in the delta set are marked as invalid tracks and
destaging to disk begins.
A new receive cycle is started.
The start of the next capture cycle and the number of cycles on the R1 side vary
depending on the version of the operating environment on the array participating in
the SRDF/A solution.
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HYPERMAX OS—Multi-cycle mode—If both arrays in the solution are running
HYPERMAX OS, SRDF/A operates in multi-cycle mode. There can be 2 or more
cycles on the R1, but only 2 cycles on the R2 side:
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On the R1 side:
– One Capture
– One or more Transmit
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On the R2 side:
– One Receive
– One Apply
Cycle switches are decoupled from committing delta sets to the next cycle.
When the preset Minimum Cycle Time is reached, the R1 data collected during the
capture cycle is added to the transmit queue and a new R1 capture cycle is
started. There is no wait for the commit on the R2 side before starting a new
capture cycle.
The transmit queue holds cycles waiting to be transmitted to the R2 side. Data in
the transmit queue is committed to the R2 receive cycle when the current
transmit cycle and apply cycle are empty.
Queuing allows smaller cycles of data to be buffered on the R1 side and smaller
delta sets to be transferred to the R2 side.
The SRDF/A session can adjust to accommodate changes in the solution. If the
SRDF link speed decreases or the apply rate on the R2 side increases, more
SRDF/A cycles can be queued the R1 side.
Multi-cycle mode increases the robustness of the SRDF/A session and reduces
spillover into the DSE storage pool.
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Enginuity 5876—If either array in the solution is running Enginuity 5876, SRDF/A
operates in legacy mode. There are 2 cycles on the R1 side, and 2 cycles on the R2
side:
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On the R1 side:
Remote replication solutions
128 Product Guide VMAX 100K, VMAX 200K, VMAX 400K with HYPERMAX OS