Installation guide

Table 4 .3. Device Attributes
Attribute Description
vendor Specifies the vendor name of the storage device to which the
device attributes apply, for example COMPAQ.
product Specifies the product name of the storage device to which the
device attributes apply, for example HSV110 (C)COMPAQ.
bl_product Specifies a regular expression used to blacklist devices by
vendor/product. Note that for a device to get blacklisted, the
vendor, product, and bl_product strings must all match.
path_grouping_policy Specifies the default path grouping policy to apply to unspecified
multipaths. Possible values include:
failover = 1 path per priority group
m ultibus = all valid paths in 1 priority group
group_by_serial = 1 priority group per detected serial number
group_by_prio = 1 priority group per path priority value
group_by_node_name = 1 priority group per target node name
getuid_callout Specifies the default program and arguments to call out to obtain a
unique path identifier. An absolute path is required.
prio_callout Specifies the default program and arguments to call out to obtain a
path weight. Weights are summed for each path group to determine
the next path group to use in case of failure. "none" is a valid value.
path_checker Specifies the default method used to determine the state of the
paths. Possible values include readsector0 and tur,
em c_clariion, hp_sw, and directio.
path_selector Specifies the default algorithm to use in determining what path to
use for the next I/O operation.
failback Specifies path group failback.
A value of 0 or im m ediate specifies that as soon as there is a
path group with a higher priority than the current path group the
system switches to that path group.
A numeric value greater than zero specifies deferred failback,
expressed in seconds.
A value of m anual specifies that failback can happen only with
operator intervention.
features T he extra features of multipath devices. The only existing feature is
queue_if_no_path, which is the same as setting
no_path_retry to queue.
hardware_handler Specifies a module that will be used to perform hardware specific
actions when switching path groups or handling I/O errors. Possible
values include 0, 1 emc, and 1 rdac. T he default value is 0.
rr_min_io (RHEL 4.8 and later) Specifies the number of I/O requests to route
to a path before switching to the next path in the current path
Red Hat Enterprise Linux 4 DM Multipath
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