
Moving
production
to
Site
B
after
unplanned
outages
(failover)
For
this
scenario,
assume
that
an
unexpected
failure
occurs
at
Site
A.
The
failure
at
Site
A
causes
the
volumes
to
be
suspended
or
causes
a
mix
of
suspended
and
full
duplex
volume
pairs
because
the
input
might
have
been
written
to
those
volumes
when
the
failure
occurred.
In
a
disaster
recovery
environment,
when
two
storage
units
are
set
up
in
two
geographically
distinct
locations,
the
storage
unit
at
the
production
or
local
site
is
referred
to
as
Site
A,
and
the
storage
unit
at
the
remote
or
recovery
site
is
referred
to
as
Site
B.
The
failover
operation
is
performed
on
the
storage
unit
that
will
become
the
primary.
Production
is
moved
to
Site
B
during
this
outage,
which
makes
the
target
volumes
at
Site
B
convert
to
source
volumes.
The
volumes
are
designated
as
in
a
suspended
state.
Your
original
source
volumes
at
Site
A
remain
in
the
state
that
they
were
in
at
the
time
of
the
site
switch.
When
Site
A
is
available
again,
application
I/O
is
switched
back
from
Site
B
to
Site
A.
The
following
steps
summarize
the
actions
you
must
take
to
move
production
to
Site
B
as
the
result
of
an
unplanned
outage
and
then
return
production
to
Site
A
after
it
recovers.
1.
Perform
a
failover
recovery
operation
to
Site
B.
After
the
failover
operation
has
processed
successfully,
the
volumes
at
Site
B
transition
from
target
to
source
volumes.
2.
Mount
your
target
volumes
on
your
server
at
Site
B.
3.
Start
your
applications
on
your
server
at
Site
B.
4.
After
Site
A
recovers,
proceed
with
the
following
steps,
which
are
the
first
steps
toward
the
recovery
of
the
volumes
at
Site
A.
a.
Create
paths
between
LSSs
at
Site
B
to
Site
A
to
allow
the
volumes
at
Site
A
to
be
synchronized
with
the
Site
B
volumes.
b.
Delete
any
remote
mirror
and
copy
volume
relationships
that
still
exist
from
the
source
volumes.
c.
Wait
until
the
volumes
are
in
full
duplex
state,
and
then
schedule
a
time
to
perform
a
failback
recovery
operation
using
the
volumes
at
Site
A.
This
process
resynchronizes
the
volumes
at
Site
A
with
the
volumes
at
Site
B.
Note:
Failback
recovery
operations
are
usually
used
after
a
failover
recovery
has
been
performed
to
restart
mirroring
either
in
the
reverse
direction
(remote
site
to
local
site)
or
in
the
original
direction
(local
site
to
remote
site).
158
DS8000
User’s
Guide
Summary of Contents for DS8000 - ADDITIONAL INFORMATION
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