
v
Management
software
provides
simple
robust
methods
that
you
can
generally
use
during
production
without
disturbing
users.
v
The
AIX
logical
volume
manager
(LVM)
provides
methods
that
you
can
use
at
any
time
without
disrupting
user
access
to
the
data.
You
might
notice
a
small
performance
degradation,
but
this
is
preferable
to
shutting
down
databases
or
requiring
users
to
log
off
the
system.
Notes:
–
AIX
and
HP-UX
11.xx
ship
with
logical
volume
management
(LVM)
software
as
part
of
the
base
operating
system.
LVM
provides
complete
control
over
all
disks
and
file
systems
that
exist
on
an
AIX
system.
HP-UX
has
similar
volume
management
software.
–
Sun
Microsystems
has
a
basic
volume
management
product
called
Solstice,
which
is
available
for
the
Solaris
systems.
–
Linux
systems
also
use
the
LVM.
v
Methods
that
use
backup
and
restore
procedures
generally
have
the
most
impact
on
the
system
usage.
They
require
that
databases
and
file
systems
be
in
quiescent
states
to
ensure
a
valid
snapshot
of
the
data.
Considerations
for
replacing
existing
storage
There
are
various
factors
to
consider
(remapping,
reformatting
of
disk
drives,
partitioning)
when
replacing
existing
storage.
When
you
are
replacing
existing
storage,
partition
the
storage
so
that
its
virtual
disks
are
similar
in
configuration
to
the
disk
drives
that
they
are
replacing.
New
configurations
must
be
large
enough
to
accommodate
the
existing
data.
Note:
You
might
want
to
take
advantage
of
this
opportunity
to
do
some
remapping.
The
allocation
and
distribution
of
data
does
not
have
to
be
a
straight
one-to-one
relationship,
although
that
is
possible.
For
instance,
you
can
take
advantage
of
using
a
maximum
of
255
logical
subsystems
whereas
the
prior
limitation
was
32
logical
subsystems.
Reformatting
disk
drive
modules
on
open
systems
To
provide
integrity-checking
of
data
and
to
allow
different
operating
systems
to
use
the
storage
unit,
IBM
formats
storage
unit
disks
to
a
524-byte
sector.
The
524-byte
sector
replaces
the
traditional
512-byte
sector
of
fixed-block
architecture
disk
drive
modules
(DDMs).
The
524-byte
sector
format
requires
that
you
reformat
all
disks
that
you
are
migrating
to
the
storage
unit.
Because
reformatting
will
erase
any
data
that
is
already
contained
on
the
drives,
you
must
back
up
the
data
to
some
form
of
temporary
storage.
You
can
use
the
DDM
for
either
direct
migration
of
data
or
as
temporary
storage
while
the
existing
drives
are
moved.
If
this
is
not
possible,
use
a
removable
media
device
such
as
a
tape
drive
to
temporarily
store
the
data
while
you
reformat
the
drives.
The
AIX
LVM
uses
a
fixed-byte
sector
of
512-bytes.
When
used
in
a
storage
unit,
the
format
is
a
fixed-byte
sector
of
524-bytes.
The
data
portion
of
the
sector
remains
at
512-bytes.
System
i
headers
use
eight
additional
bytes.
A
2-byte
sequence
number
and
a
2-byte
longitudinal
redundancy
check
(LRC)
complete
the
142
DS8000
User’s
Guide
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