Technical data

Table 3 HP Recommended configuration parameters
Attribute
Description
Supported values
path_grouping_pol-
icy
Used for applying the policy to the multipath device
hosted by this storage controller
multibus: All valid paths in one priority
group
group_by_prio: One priority group per
path priority value
path_checker
Used for determining the state of the path
tur
path_selector
Used to select the path selector algorithm to be used
for mpath. These algorithms are offered by the kernel
mpath target
round-robin 0
failback
Used to manage the time during path group failback
immediate
prio_callout
Executable to ob tain a path weight for a block device.
Weights are summed for each path group to determine
the next path group to be used in case of path failure
/bin/true
/sbin/mpath_prio_alua %n
rr_weight
Used to assign weights to the path uniform
no_path_retry
(n =12) indicates the number of retries u ntil queuing is
disabled (queues till n number of polling) , fail indicates
immediate failure (no queuing), or queue indicates never
stop queuing (queue forever till the path comes alive)
n=12
Example 1. Recomme nded Values for HP Arrays
The product string of the storage controller contains 16 characters (including spaces) and the vendor
string contains 8 characters (including spaces) in the /etc/multipath.conf file. To ease the task of
manually editing the devices section of the multipath.conf file, the wild card, regular expression
support for the product and vendor string is provided. For example, in /etc/multipath.conf
file, the product string for the HSV101 arrays is given the value of HSV101*,insteadofHSV101
\(C\)COMPAQ.
For EVA3000-(HSV101)
device
{
vendor
product
path_grouping_policy
getuid_callout
path_checker
path_selector
prio_callout
rr_weight
rr_min_io
failback
no_path_retry
"HP"
"HSV101 \(C\)COMPAQ"
group_by_prio
"/sbin/scsi_id -g -u -s /block/%n"
tur
"round-robin 0"
"/sbin/mpath_prio_alua %n"
uniform
100
immediate
12
}
14
Configuring HPDM Multipath