scsimgr_esdisk(7)scsimgr_esdisk(7)NAMEscsimgr_esdisk - SCSI class driver esdisk plug-in for scsimgr
DESCRIPTION
The SCSI class driver plug-in for implements management and diagnostic
operations specific to classes of devices bound to the driver. is the
native HP-UX SCSI class driver that handles, by default, all block
devices including the following types: direct access, CD/DVD, write-
once read-multiple (WORM), and optical memory (OM).
The plug-in handles the following operations for driver
· Displays and clears driver global statistics and the statistics it
maintains on instances of LUNs bound to it, and on related LUN
paths.
· Displays status and other information maintained by driver on LUNs
bound to it.
· Gets, sets, and saves driver global, per-lun instance attributes
or attributes for a set of devices bound to the driver.
Commands
The user can explicitly send the following commands to driver plug-in
by specifying the option:
Clears statistics.
Displays information on attributes.
Displays status and other information.
Displays statistics.
Saves value of attributes in a persistent store.
Set current values of attributes.
Refer to scsimgr(1M) for the syntax of the above commands.
However, the only instance when it is necessary to explicitly send a
command to the plug-in is when performing operations on objects global
to driver global statistics, attributes or status information. In all
the other cases, automatically invokes the plug-in to perform the
driver specific part of the operation, when the operation applies to
LUNs bound to driver or to their LUN paths.
Attributes
The following table lists driver specific attributes. Under the cate‐
gory "Device Set", the table lists which attributes the driver allows
at a settable attribute scope (also known as Device Data Repository,
DDR). Attribute scopes supported by are peripheral device type (pdt),
vendor identifier (vid), product identifier (pid), and product revision
(rev). See attr_scope in scsimgr(1M) for more information.
The following conventions are used :
· RO is Read Only.
· RW is Read Write.
· uint32 is unsigned 32 bit integer.
· Range of values for applicable attributes is listed.
───────────────────────────────────────────────────────────────────
Object Attribute Name RO/RW Type Description
───────────────────────────────────────────────────────────────────
Global version RO string Version of driver
esdisk.
───────────────────────────────────────────────────────────────────
LUN capacity RO uint32 Device capacity in
number of blocks.
───────────────────────────────────────────────────────────────────
congest_max_retries RW uint32 Number of retries
for device discovery
I/Os during Busy or
Queue Full condi‐
tion.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
block_size RO uint32 Block size in bytes.
───────────────────────────────────────────────────────────────────
format_secs RW uint32 Timeout in seconds
of SCSI command FOR‐
MAT.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
start_unit_secs RW uint32 Timeout in seconds
of SCSI command
START UNIT.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
max_retries RW uint32 Maximum number of
I/O retries.
Range: 1 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
path_fail_secs RW uint32 Timeout in seconds
before declaring a
LUN path offline.
Range: 0 -
0xFFFFFFFE
───────────────────────────────────────────────────────────────────
esd_secs RW uint32 Maximum time in sec‐
onds for the trans‐
mission of an I/O.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
load_bal_policy RW string I/O load balancing
policy.
May be:
round_robin
least_cmd_load
cl_round_robin
closest_path
preferred_path
pref_tport
weighted_rr
───────────────────────────────────────────────────────────────────
infinite_retries RW boolean Enable or disable
_enable infinite retry of
I/Os.
May be:
true (1): enable
false (0): disable
───────────────────────────────────────────────────────────────────
disable_flags RW string A set of flags rep‐
resenting SCSI task
management and other
functions. If a
flag is set, the
corresponding func‐
tion is disabled for
the LUN, except for
the ABT_LPT flag
(see below for
details).
The following flags
are currently
defined:
WCE: Write Cache
Enable
RW16: 16 bytes
READ/WRITE CDB
ABT: SCSI task man‐
agement function
Abort Task Set
CTS: SCSI task man‐
agement function
Clear Task Set
LR: SCSI task man‐
agement function LUN
Reset
WTR: SCSI task man‐
agement function
Warm Target Reset
CTR: SCSI task man‐
agement function
Cold Target Reset
BR: Bus Reset
PR: Persistent
Reservation
WERO: Write Exclu‐
sive Registrants
Only Persistent
Reservation
EARO: Exclusive
Access Registrants
Only Persistent
Reservation
ABT_LPT: Delay the
SCSI task management
function Abort Task
Set, to allow out‐
standing I/O
requests to com‐
plete.
NOTE: This flag has
no significance if
the ABT flag,
described above, is
set
ALL: Disable all
functions
NONE: Enable all
functions
───────────────────────────────────────────────────────────────────
preferred_path RW string Hardware path, or
class and instance
number of the LUN
path to use prefer‐
ably for I/O trans‐
fer, when I/O load
balancing policy is
set to pre‐
ferred_path.
───────────────────────────────────────────────────────────────────
pref_tport RW string Worldwide name (WWN)
in hexadecimal of
the target port to
use preferably for
I/O transfer, when
I/O load balancing
policy is set to
pref_tport.
───────────────────────────────────────────────────────────────────
alua_enabled RW boolean Indicates whether
Asymmetric Logical
Unit Access (ALUA)
functionality is
enabled for the LUN
instance. The value
of true (1) indi‐
cates that ALUA
functionality is
handled if LUN sup‐
ports it. The value
of false (0) indi‐
cates that ALUA
functionality is
ignored even if LUN
supports it.
May be:
true (1): enable
ALUA
false (0): disable
ALUA
───────────────────────────────────────────────────────────────────
retry_delay RW boolean Enables or disables
_enabled support of retry
delay timer codes
returned by devices
complying with SAM-4
(SCSI Architecture
Model 4), in case of
congestion. If set
to false (0), retry
delay timer codes
are ignored. If set
to true (1), retry
delay timer codes
are taken into con‐
sideration, when
handling congestion.
May be:
true (1): enable
retry delay timer
codes.
false (0): disable
disable retry timer
codes.
───────────────────────────────────────────────────────────────────
ping_type RW string Failed LUN path con‐
nectivity test.
Determines whether
the system should
automatically test
the connectivity of
a failed LUN path
and if so which kind
of test must be per‐
formed.
May be set to:
No connectivity test
should be performed.
Basic connectivity
test including the
Standard Inquiry
command, should be
performed.
Extended connectiv‐
ity test including
Standard Inquiry and
Test Unit Ready
(TUR) commands
should be performed.
───────────────────────────────────────────────────────────────────
ping_recovery RW string Failed LUN path
recovery policy.
Determines when a
failed LUN path
should be considered
back online when
automatic connectiv‐
ity test is enabled.
May be set to:
Upon a successful
connectivity test.
After a number of
consecutive success‐
ful connectivity
tests specified by
the attribute
Upon sustained suc‐
cessful connectivity
tests within the
time period speci‐
fied in the
attribute
───────────────────────────────────────────────────────────────────
ping_time _thresh‐ RW uint32 Minimum time in sec‐
old onds, of sustained
successful connec‐
tivity tests before
a failed LUN path is
considered back
online.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
ping_count _thresh‐ RW uint32 Minimum number of
old consecutive success‐
ful connectivity
tests before a
failed LUN path is
considered back
online.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
Device Set transient_secs RW uint32 Seconds to wait
after a LUN transi‐
tioned out of ONLINE
state before failing
I/Os.
Range: 0 -
0xFFFFFFFE
───────────────────────────────────────────────────────────────────
congest_max_retries RW uint32 Number of retries
for device discovery
I/Os during Busy or
Queue Full condi‐
tion.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
format_secs RW uint32 Timeout in seconds
of SCSI command FOR‐
MAT.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
start_unit_secs RW uint32 Timeout in seconds
of SCSI command
START UNIT.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
max_retries RW uint32 Maximum number of
I/O retries.
Range: 1 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
path_fail_secs RW uint32 Timeout in seconds
before declaring a
LUN path offline.
Range: 0 -
0xFFFFFFFE
───────────────────────────────────────────────────────────────────
esd_secs RW uint32 Maximum time in sec‐
onds for the trans‐
mission of an I/O.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
max_q_depth RW uint32 Maximum queue depth.
Range: 1 -
0xFFFFFFFE
───────────────────────────────────────────────────────────────────
load_bal_policy RW string I/O load balancing
policy.
May be set to:
round_robin
least_cmd_load
cl_round_robin
closest_path
weighted_rr
───────────────────────────────────────────────────────────────────
alua_enabled RW boolean Indicates whether
Asymmetric Logical
Unit Access (ALUA)
functionality is
enabled by default.
A value of true (1)
indicates that by
default ALUA func‐
tionality will be
handled for the
devices supporting
it. A value of
false (0) indicates
that by default ALUA
functionality will
be ignored for the
devices supporting
it.
May be:
true (1): enable
ALUA
false (0): disable
ALUA
───────────────────────────────────────────────────────────────────
disable_flags RW string A set of flags rep‐
resenting SCSI task
management and other
functions. If a
flag is set, the
corresponding func‐
tion is disabled for
the set of devices,
except for the
ABT_LPT flag (see
below for details).
The following flags
are currently
defined:
WCE: Write Cache
Enable
RW16: 16 bytes
READ/WRITE CDB
ABT: SCSI task man‐
agement function
Abort Task Set
CTS: SCSI task man‐
agement function
Clear Task Set
LR: SCSI task man‐
agement function LUN
Reset
WTR: SCSI task man‐
agement function
Warm Target Reset
CTR: SCSI task man‐
agement function
Cold Target Reset
BR: Bus Reset
PR: Persistent
Reservation
WERO: Write Exclu‐
sive Registrants
Only Persistent
Reservation
EARO: Exclusive
Access Registrants
Only Persistent
Reservation
ABT_LPT: Delay the
SCSI task management
function Abort Task
Set, to allow out‐
standing I/O
requests to com‐
plete.
NOTE: This flag has
no significance if
the ABT flag,
described above, is
set
ALL: Disable all
functions
NONE: Enable all
functions
───────────────────────────────────────────────────────────────────
infinite_retries RW Boolean Enable or disable
_enable infinite retries of
I/Os
May be:
true (1): enable
false (0): disable
───────────────────────────────────────────────────────────────────
retry_delay RW boolean Enables or disables
_enabled support of retry
delay timer codes
returned by devices
complying with SAM-4
(SCSI Architecture
Model 4), in case of
congestion. If set
to false (0), retry
delay timer codes
are ignored. If set
to true (1), retry
delay timer codes
are taken into con‐
sideration, when
handling congestion.
May be:
true (1): enable
retry delay timer
codes.
false (0): disable
disable retry delay
timer codes.
───────────────────────────────────────────────────────────────────
ping_type RW string Failed LUN path con‐
nectivity test.
Determines whether
the system should
automatically test
the connectivity of
a failed LUN path
and if so which kind
of test must be per‐
formed.
May be set to:
No connectivity test
should be performed.
Basic connectivity
test including Stan‐
dard Inquiry com‐
mand, should be per‐
formed.
Extended connectiv‐
ity test including
Standard Inquiry and
Test Unit Ready
(TUR) commands
should be performed.
───────────────────────────────────────────────────────────────────
ping_recovery RW string Failed LUN path
recovery policy.
Determines when a
failed LUN path
should be considered
back online when
automatic connectiv‐
ity test is enabled.
May be set to:
Upon a successful
connectivity test.
after a number of
consecutive success‐
ful onnectivity
tests specified by
the attribute
Upon sustained suc‐
cessful connectivity
tests within the
time period speci‐
fied in the
attribute
───────────────────────────────────────────────────────────────────
ping_time _thresh‐ RW uint32 Minimum time in sec‐
old onds, of sustained
successful connec‐
tivity tests before
a failed LUN path is
considered back
online.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
ping_count _thresh‐ RW uint32 Minimum number of
old consecutive success‐
ful connectivity
tests before a
failed LUN path is
considered back
online.
Range: 0 -
0xFFFFFFFF
───────────────────────────────────────────────────────────────────
I/O Load Balancing Policy
The I/O load balancing policy attribute, is a tunable that controls how
I/Os are distributed across the paths to a LUN:
·
LUN paths are selected in a round robin manner. This is more
appropriate when all the paths to the device have similar I/O
turn-around characteristics.
·
The LUN path with the least number of active I/O requests is
selected to execute the next I/O. This policy is appropriate when
the paths to the LUN exhibit asymmetric latency characteristics.
The load is distributed to optimize the bandwidth on each LUN
path.
·
This load balancing policy is applicable to HP cell-based plat‐
forms. The LUN paths are selected in a round robin manner within
the locality of CPU on which the I/O was initiated, to ensure that
memory access latencies are optimized.
·
The LUN path set in the attribute is preferably used for I/O
transfer. If this LUN path is not available or if the attribute
was not set, any other path is selected for I/O transfer. This
policy is useful for certain disk arrays, where some paths may be
optimized for I/O transfer to certain LUNs.
The attribute can be set with the hardware path, or the combina‐
tion of the class and instance number of the preferred LUN path.
For example for a LUN path with instance number 100, the combina‐
tion of class and instance number is: In a normal output display
for this attribute, both the hardware path and the combination of
class and instance number of the preferred LUN path are displayed
(Example: In scriptable output for this attribute, only the hard‐
ware path of the preferred LUN path is displayed (Example:
·
The LUN path is selected based on its affinity with the CPU issu‐
ing the I/O so as to minimize latency. This policy is more appro‐
priate on cell based platforms.
·
LUN paths to the target port set in the attribute are preferably
used for I/O transfer in a round robin manner, when the I/O load
balancing policy is set to If no LUN path to the preferred target
port is available, or if the attribute is not set, any other path
is selected for I/O transfer. This policy is appropriate for cer‐
tain disk arrays, where some target ports are optimized for I/O
transfer to certain LUNs.
·
Weighted Round Robin. I/Os are distributed between the LUN paths
in a round robin manner and according to the weight assigned to
each path (via the LUN path attribute A number of I/Os correspond‐
ing to the weight of the path is transferred on the path before
another path is selected.
EXAMPLES
To display plug-in general help and supported commands:
To get esdisk driver global statistics:
To clear esdisk driver global statistics:
To get esdisk driver global status information:
To display information about esdisk driver global attributes:
To set the I/O load balancing policy for disk0 to and set the I/O path
to be used preferably:
To set the I/O load balancing policy for disk1 to and set the preferred
target port to 0x50001fe150006e6d:
To add a settable attribute scope corresponding to all disk devices
from HP with product identifier "MSA VOLUME", for allowing modification
of some settable attribute at this scope:
To persistently change the default I/O load balancing policy, I/O time‐
out, and maximum concurrent I/O for all disk devices from HP with
product identifier "MSA VOLUME:"
To disable write cache, Persistent Reservation and 16 bytes read/write
CDB for all disk devices bound to the driver:
AUTHOR
SCSI class driver plug-in for was developed by Hewlett-Packard Company.
SEE ALSOdiskinfo(1M), scsictl(1M), scsimgr(1M), intro(7), scsi(7),
scsi_disk(7).
scsimgr_esdisk(7)
