Oracle ASM Multipath Problem

Hi,

We have some EMC VNX storage arrays for Oracle DB servers and we are using native multipathing on Oracle Linux 6.5.
There is a problem about LUN trespass between multipath and ASM.
When one of SPs is rebooted, all disks are in Missing status in ASM. I don't know why ASM can't use disks when those disks are trespassed to another SP and another path group.
In addition of the rebooted SP's LUNs, other LUNs will be missed!
Here is our device configurations in multipath.conf:

defaults {
udev_dir /dev
polling_interval 5
path_selector "round-robin 0"
path_grouping_policy group_by_prio
getuid_callout "/lib/udev/scsi_id --whitelisted --device=/dev/%n"
prio alua
path_checker tur
rr_min_io 100
max_fds max
rr_weight uniform
failback immediate
no_path_retry fail
features "0"
user_friendly_names yes
}