HP EVA6400存储提供的Preferred path/mode有4个选项。如图 :
默认情况下是No preference.
假设LINUX multipath.conf配置如下 ：
blacklist {
devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
devnode "^hd[a-z]"
devnode "^sda$"
#devnode "^cciss!c[0-9]d[0-9]*"
}
defaults {
udev_dir /dev
polling_interval 10
selector "round-robin 0"
path_grouping_policy failover
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
prio_callout /bin/true
path_checker readsector0
rr_min_io 100
rr_weight priorities
failback immediate
no_path_retry fail
user_friendly_names yes
flush_on_last_del yes
}
multipaths {
multipath {
wwid 36001438005de97860000b00001400000
alias e06_eva_vd13
}
}
在操作系统中查看multipath时可以看到类似如下输出。
multipath -ll
e06_eva_vd13 (36001438005de97860000b00001400000) dm-0 HP,HSV400
[size=600G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=100][active]
\_ 1:0:0:1 sdb 8:16 [active][ready]
\_ 2:0:0:1 sdd 8:48 [active][ready]
\_ round-robin 0 [prio=20][enabled]
\_ 1:0:1:1 sdc 8:32 [active][ready]
\_ 2:0:1:1 sde 8:64 [active][ready]
修改为Path B-Failover/failback后，得到如下结果。
multipath -ll
e06_eva_vd13 (36001438005de97860000b00001400000) dm-0 HP,HSV400
[size=600G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=20][active]
\_ 1:0:0:1 sdb 8:16 [active][ready]
\_ 2:0:0:1 sdd 8:48 [active][ready]
\_ round-robin 0 [prio=100][enabled]
\_ 1:0:1:1 sdc 8:32 [active][ready]
\_ 2:0:1:1 sde 8:64 [active][ready]
Preferred path/mode可以在线修改。