n
If all the SRDF device pairs are Not Ready (NR) on the link, createpair
operations can add devices to the group if the new device pairs are created Not
Ready (NR) on the link.
n
If all the SRDF device pairs are Not Ready (NR) on the link, deletepair
operations can delete a subset of the SRDF devices in the SRDF group.
l
In the event of link or other failures, SRDF/Metro provides the following methods
for determining which side of a device pair remains accessible to the host:
n
Bias option: Device pairs for SRDF/Metro are created with a new attribute
-
use_bias
. By default, the createpair operation sets the bias to the R1 side of
the pair. That is, if the device pair becomes Not Ready (NR) on the RDF link,
the R1 (bias side) remains accessible to the host(s), and the R2 (non-bias side)
is inaccessible to the host(s).
When all RDF device pairs in the RDF group have reached the ActiveActive or
ActiveBias pair state, bias can be changed (so the R2 side of the device pair
remains accessible to the host).
on page 149 provides more information.
n
Witness option: A designated Witness monitors SRDF on each array and the
SRDF links between them. In the event of a failure, the Witness can determine
the nature of the failure, and arbitrate which side of the device pair becomes
the non-bias side (inaccessible to hosts) and which side becomes the bias side
(remains accessible to hosts). The Witness method allows for intelligently
choosing on which side to continue operations when the bias-only method may
not result in continued host availability to a surviving non-biased array.
The Witness option is the default.
SRDF/Metro provides two types of Witnesses, Array and Virtual:
– Witness Array : HYPERMAX OS or Enginuity on a third array monitors
SRDF/Metro, determines the type of failure, and uses the information to
choose one side of the device pair to remain R/W accessible to the host.
The Witness option requires two SRDF groups: one between the R1 array
and the Witness array and the other between the R2 array and the Witness
array.
on page 150 provides more information. The component on
the Array Witness .
– Virtual Witness option: Introduced with HYPERMAX OS 5977 Q3 2016 SR,
vWitness provides the same functionality as the Witness Array option, only
it is packaged to run in a virtual appliance, not on the array.
SRDF/Metro integration with FAST
When the SRDF/Metro configuration reaches Active mode and device pairs reach
ActiveActive pair state, exchange of performance begins. Each side incorporates the
FAST statistics from the other side ensuring that each side represents the workload as
a whole (R1+R2 workload).
Users may set the SL independently on both source and target SRDF/Metro paired
arrays.
SRDF/Metro life cycle
The life cycle of an SRDF/Metro configuration begins and ends with an empty SRDF
group and a set of non-SRDF devices, as shown in the following image.
Remote replication solutions
SRDF/Metro integration with FAST
147
Содержание VMAX 100K
Страница 1: ...EMC VMAX3 Family Product Guide VMAX 100K VMAX 200K VMAX 400K with HYPERMAX OS REVISION 6 5 ...
Страница 20: ...Preface 20 Product Guide VMAX 100K VMAX 200K VMAX 400K with HYPERMAX OS ...
Страница 46: ...VMAX3 with HYPERMAX OS 46 Product Guide VMAX 100K VMAX 200K VMAX 400K with HYPERMAX OS ...
Страница 72: ...Open systems features 72 Product Guide VMAX 100K VMAX 200K VMAX 400K with HYPERMAX OS ...
Страница 82: ...Provisioning 82 Product Guide VMAX 100K VMAX 200K VMAX 400K with HYPERMAX OS ...
Страница 100: ...Native local replication with TimeFinder 100 Product Guide VMAX 100K VMAX 200K VMAX 400K with HYPERMAX OS ...
Страница 158: ...Remote replication solutions 158 Product Guide VMAX 100K VMAX 200K VMAX 400K with HYPERMAX OS ...
Страница 186: ...Mainframe Error Reporting 186 Product Guide VMAX 100K VMAX 200K VMAX 400K with HYPERMAX OS ...
Страница 200: ...Licensing 200 Product Guide VMAX 100K VMAX 200K VMAX 400K with HYPERMAX OS ...