Dell PowerStore 5200T EMC PowerStore Host Configuration Guide - Page 66

Parameter, Description, Value, Applies to Red Hat Enterprise Linux Release 6.9 or later 6.x

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## other devices } Parameter disable_changed_wwids vendor product path_selector path_grouping_policy path_checker detect_prio failback no_path_retry rr_min_io_rq fast_io_fail_tmo max_sectors_kb Description Value If set to yes, and the WWID of a path device changes while it is yes part of a multipath device, multipath disables access to the path device until the WWID of the path is restored to the WWID of the multipath device. The default value is no (does not check if the WWID of the path has changed). Specifies the vendor name DellEMC The below configuration applies only to PowerStore volumes. PowerStore Sends the next group of I/Os to the path with the least number of queue-length 0 outstanding I/O requests Specifies the default path grouping policy to apply to PowerStore volumes ● Paths are grouped by priorities that are assigned by the cluster. ● A higher priority (50) is set as Active/Optimized. Lower priority (10) is set as Active/Non-Optimized. group_by_prio Specifies TEST UNIT READY as the default method used to tur determine the state of the paths. If set to yes, multipath tries to detect whether the device yes supports ALUA. If so, the device automatically uses the alua prioritizer. Otherwise, the prioritizer is selected as usual. Default value is no. Manages the path group failback. Immediate refers to Immediate immediate failback to the highest priority path group that contains active paths. Specifies the number of times the system should attempt to use a 3 failed path before disabling queuing. Specifies the number of I/O requests to route to a path before 1 switching to the next path in the same path group, using requestbased device-mapper-multipath. This setting should be used on systems running current kernels. On systems running kernels older than 2.6.31, use rr_min_io. Default value is 1. Specifies the number of seconds the scsi layer will wait after a 15 problem has been detected on an FC remote port before failing I/O to devices on that remote port. This value should be smaller than dev_loss_tmo. Setting this parameter to off disables the timeout. Applies to Red Hat Enterprise Linux Release 6.9 (or later 6.x versions) and Red Hat Enterprise Linux Release 7.4 (or later 7.x versions). Sets the max_sectors_kb device queue parameter to the specified value on all underlying paths of a multipath device before the multipath device is first activated. When a multipath device is created, the device inherits the max_sectors_kb value from the path devices. Manually raising this value for the multipath device or lowering it for the path devices can cause multipath to create I/O operations larger than the path devices allow. Using the max_sectors_kb parameter is an easy way to set these values before a multipath device is created on top of the path devices and prevent invalid-sized I/O operations from being passed. If this parameter is not set by the user, the path 1024 66 Host Configuration for Linux

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## other devices
}
Parameter
Description
Value
disable_changed_wwids
If set to yes, and the WWID of a path device changes while it is
part of a multipath device, multipath disables access to the path
device until the WWID of the path is restored to the WWID of the
multipath device. The default value is no (does not check if the
WWID of the path has changed).
yes
vendor
Specifies the vendor name
DellEMC
product
The below configuration applies only to PowerStore volumes.
PowerStore
path_selector
Sends the next group of I/Os to the path with the least number of
outstanding I/O requests
queue-length 0
path_grouping_policy
Specifies the default path grouping policy to apply to PowerStore
volumes
●
Paths are grouped by priorities that are assigned by the
cluster.
●
A higher priority (50) is set as Active/Optimized. Lower
priority (10) is set as Active/Non-Optimized.
group_by_prio
path_checker
Specifies TEST UNIT READY as the default method used to
determine the state of the paths.
tur
detect_prio
If set to yes, multipath tries to detect whether the device
supports ALUA. If so, the device automatically uses the alua
prioritizer. Otherwise, the prioritizer is selected as usual. Default
value is no.
yes
failback
Manages the path group failback.
Immediate
refers to
immediate failback to the highest priority path group that contains
active paths.
Immediate
no_path_retry
Specifies the number of times the system should attempt to use a
failed path before disabling queuing.
3
rr_min_io_rq
Specifies the number of I/O requests to route to a path before
switching to the next path in the same path group, using request-
based device-mapper-multipath. This setting should be used on
systems running current kernels. On systems running kernels older
than 2.6.31, use
rr_min_io
. Default value is 1.
1
fast_io_fail_tmo
Specifies the number of seconds the scsi layer will wait after a
problem has been detected on an FC remote port before failing
I/O to devices on that remote port. This value should be smaller
than
dev_loss_tmo
. Setting this parameter to off disables the
timeout.
15
max_sectors_kb
Applies to Red Hat Enterprise Linux Release 6.9 (or later 6.x
versions) and Red Hat Enterprise Linux Release 7.4 (or later 7.x
versions).
Sets the
max_sectors_kb
device queue parameter to the
specified value on all underlying paths of a multipath device
before the multipath device is first activated. When a multipath
device is created, the device inherits the
max_sectors_kb
value from the path devices. Manually raising this value for the
multipath device or lowering it for the path devices can cause
multipath to create I/O operations larger than the path devices
allow. Using the
max_sectors_kb
parameter is an easy way to
set these values before a multipath device is created on top of
the path devices and prevent invalid-sized I/O operations from
being passed. If this parameter is not set by the user, the path
1024
66
Host Configuration for Linux