Appendix d. enabling lun support in linux, Appendix, Enabling – Dell TL2000 User Manual
Page 239: Support, Linux
Appendix
D.
Enabling
LUN
Support
in
Linux
To
verify
the
detection
of
a
tape
drive,
administrators
should
check
for
its
entry
in
/proc/scsi/scsi
.
Current
versions
of
Linux
may
not
scan
the
logical
storage
unit
(LUN)
ID
of
every
device.
This
can
result
in
some
PowerVault
devices
not
being
identified
or
listed
in
the
/proc/scsi/scsi
output.
Administrators
can
follow
these
steps
to
enable
support
for
such
devices.
1.
Type
cat/proc/scsi/scsi
.
The
output
will
look
similar
to
the
following:
Attached
devices:
Host:
scsi3
Channel:
00
Id:
00
Lun:
00
Vendor:
IBM
Model:
ULTRIUM-TD3
Rev:
5BG2
Type:
Sequential-Access
ANSI
SCSI
revision:
03
2.
Identify
the
host
adapter,
channel
number,
target
ID
number,
and
LUN
number
for
the
first
LUN
of
the
device
to
be
configured.
In
this
example,
the
Certance
Ultrium
2
(a
drive
in
the
PowerVault
124T)
is
shown
at
the
address,
or
nexus,
3
0
0
0
—
which
means
host
adapter
3,
channel
number
0,
ID
0,
and
LUN
0.
The
PowerVault
124T
always
has
the
tape
drive
at
LUN
0
and
the
robot
at
LUN
1.
3.
For
each
LUN
that
needs
to
be
discovered
by
Linux,
issue
the
following
command:
echo
"scsi-add-single-device
H
C
I
L">/proc/scsi/scsi
H
C
I
L
refers
to
the
nexus
described
in
step
2.
So,
with
the
PowerVault
124T
robot
configured
at
LUN
1,
type:
echo
"scsi-add-single-device
3
0
0
1">/proc/scsi/scsi
.
The
echo
command
will
force
a
scan
of
each
device
at
the
given
nexus.
4.
Type
cat
/proc/scsi/scsi
again
to
verify
that
all
devices
are
now
listed.
The
output
will
look
similar
to
the
following:
Attached
devices:
Host:
scsi3
Channel:
00
Id:
00
Lun:
00
Vendor:
IBM
Model:
ULTRIUM-TD3
Rev:
5BG2
Type:
Sequential-Access
ANSI
SCSI
revision:
03
Attached
devices:
Host:
scsi3
Channel:
00
Id:
00
Lun:
01
Vendor:
DELL
Model:
PV-124T
Rev:
V31
Type:
Sequential-Access
ANSI
SCSI
revision:
03
Administrators
should
add
the
echo
command
to
the
Linux
boot
scripts
because
the
device
information
is
not
persistent
and
must
be
created
each
time
the
system
boots
up.
One
example
file
that
can
be
used
for
storing
the
commands
is
/etc/rc.local.
Note
that
configuring
additional
devices
on
a
server
or
a
storage
area
network
(SAN)
can
cause
the
devices
to
be
reordered,
which
requires
administrators
to
modify
the
commands.
If
the
Fibre
Channel
adapter
supports
Persistent
Bindings
or
an
equivalent
function,
it
can
be
enabled
to
reduce
the
chance
of
devices
being
reordered
upon
discovery.
Note:
This
procedure
must
be
run
each
time
the
server
is
booted.
Also,
if
backup
application
services
are
running
(for
example,
they
automatically
start
when
the
OS
loads),
they
must
be
disabled
and
re-enabled
after
the
above
procedure.
The
other
way
to
enable
LUN
support
is
to
recompile
the
kernel
and
enable
LUN
scanning
in
the
Adaptec
driver,
but
it
requires
advanced
knowledge
of
Linux
and
will
not
be
covered
here.
However,
it
will
allow
the
server
to
always
boot
and
see
the
device
without
any
manual
procedures.
D-1