EMC VMAX 100K, Руководство по эксплуатации продукта

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corresponding R2 device. The background copy process scheduled to send I/Os from
the R1 to the R2 devices can be deferred if:
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The write requests exceed the maximum R2 write pending limits, or
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The write requests exceed 50 percent of the primary or secondary array write
pending space.
Adaptive copy write pending
In adaptive copy write pending mode, write requests accumulate in cache on the
primary array. A background process sends the outstanding write requests to the
corresponding R2 device.
Adaptive copy write-pending mode reverts to the primary mode if the device, cache
partition, or system write pending limit is near, regardless of whether the maximum
skew value specified for each device is reached.
Domino modes
Under typical conditions, when one side of a device pair becomes unavailable, new
data written to the device is marked for later transfer. When the device or link is
restored, the two sides synchronize.
Domino modes force SRDF devices into the Not Ready state to the host if one side of
the device pair becomes unavailable.
Domino mode can be enabled/disabled at:
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Device level (domino mode) – If the R1 device cannot successfully mirror data to
the R2 device, the next host write to the R1 device causes the device to become
Not Ready to the host connected to the primary array.
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SRDF group level (link domino mode) – If the last available link in the SRDF group
fails, the next host write to any R1 device in the SRDF group causes all R1 devices
in the SRDF group become Not Ready to their hosts.
Link domino mode is set at the SRDF group level and only impacts devices where the
R1 is on the side where it is set.
SRDF groups
SRDF groups define the relationships between the local SRDF instance and the
corresponding remote SRDF instance.
All SRDF devices must be assigned to an SRDF group. Each SRDF group
communicates with its partner SRDF group in another array across the SRDF links.
Each SRDF group points to one (and only one) remote array.
An SRDF group consists of one or more SRDF devices, and the ports over which those
devices communicate. The SRDF group shares CPU processing power, ports, and a
set of configurable attributes that apply to all the devices in the group, including:
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Link Limbo and Link Domino modes
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Autolink recovery
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Hardware and software compression
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SRDF/A:
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Cycle time
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Session priority
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Pacing delay and threshold
Remote replication solutions
124 Product Guide VMAX 100K, VMAX 200K, VMAX 400K with HYPERMAX OS