
The
Metro/Global
Mirror
function
provides
this
combination
of
synchronous
and
asynchronous
mirroring.
Metro/Global
Mirror
is
an
extension
of
Global
Mirror,
which
is
based
on
existing
Global
Copy
(formerly
known
as
PPRC
XD)
and
FlashCopy
functions.
Global
Mirror
running
at
the
intermediate
site,
using
a
master
storage
unit
and
optional
subordinate
storage
units,
internally
manages
data
consistency,
removing
the
need
for
external
software
to
form
consistency
groups
at
the
remote
site.
shows
the
three
sites
that
are
used
in
a
Metro/Global
Mirror
configuration.
The
configuration
uses
a
minimum
of
three
storage
units,
one
each
at
the
local,
intermediate,
and
remote
sites.
A
minimum
of
four
volumes
(volume
A,
volume
B,
volume
C,
and
volume
D)
are
used
in
this
configuration.
(For
ease
of
description,
the
Metro/Global
Mirror
configuration
is
described
using
these
volumes.
Some
environments
can
contain
hundred
or
thousands
of
volumes.)
Data
from
the
A
volumes
at
the
local
site
is
synchronously
replicated
to
the
B
volumes
at
the
intermediate
site
using
Metro
Mirror.
Data
from
the
B
volumes
at
the
intermediate
site
is
asynchronously
replicated
to
the
C
volumes
at
the
remote
site
using
Global
Copy.
FlashCopy
relationships
are
created
with
the
C
volumes
at
the
remote
site
as
the
FlashCopy
source
volumes
and
the
D
volumes
at
the
remote
site
as
the
FlashCopy
target
volumes,
maintaining
the
consistent
disaster
recovery
volumes
using
Global
Mirror.
As
an
additional
layer
of
disaster
protection
if
Global
Mirror
processing
were
to
fail
at
the
remote
site,
you
can
use
the
storage
at
your
intermediate
site
for
a
target
copy.
Setting
up
Global
Mirror
between
the
remote
and
intermediate
sites
requires
an
additional
set
of
FlashCopy
volumes
at
the
intermediate
site.
Then,
you
can
perform
failover
and
restore
operations
at
the
remote
site
using
these
volumes
at
the
intermediate
site
(acting
as
a
remote
site)
to
create
Global
Mirror
consistency
groups.
These
volumes,
which
are
referred
to
as
E
volumes,
would
be
used
as
FlashCopy
targets
for
a
Global
Mirror
consistency
group.
Metro Mirror
Global Copy
A
B
C
D
FlashCopy
Local Site
Intermediate Site
Remote Site
f2c00503
Metro Global Mirror
Global
Mirror
E
Figure
11.
Metro/Global
Mirror
configuration
Chapter
8.
Optional
feature
codes
for
the
DS8000
119
Summary of Contents for DS8000 - ADDITIONAL INFORMATION
Page 1: ...IBM System Storage DS8000 User s Guide V ersion 1 Release 4 SC26 7915 02 ...
Page 2: ......
Page 3: ...IBM System Storage DS8000 User s Guide V ersion 1 Release 4 SC26 7915 02 ...
Page 8: ...vi DS8000 User s Guide ...
Page 10: ...viii DS8000 User s Guide ...
Page 12: ...x DS8000 User s Guide ...
Page 14: ...xii DS8000 User s Guide ...
Page 26: ...xxiv DS8000 User s Guide ...
Page 106: ...78 DS8000 User s Guide ...
Page 168: ...140 DS8000 User s Guide ...
Page 202: ...174 DS8000 User s Guide ...
Page 204: ...176 DS8000 User s Guide ...
Page 212: ...184 DS8000 User s Guide ...
Page 242: ...214 DS8000 User s Guide ...
Page 246: ...218 DS8000 User s Guide ...
Page 249: ......
Page 250: ... Printed in USA SC26 7915 02 ...