Howo to get Multipath IO with Dell MD3600i into active/active setup?
- by Disco
I'm desperately trying to improve performance of my SAN connection.
Here's what i have:
[root@xnode1 dell]# multipath -ll
mpath1 (36d4ae520009bd7cc0000030e4fe8230b) dm-2 DELL,MD36xxi
[size=5.5T][features=3 queue_if_no_path pg_init_retries 50][hwhandler=1 rdac][rw]
\_ round-robin 0 [prio=200][active]
\_ 18:0:0:0 sdb 8:16 [active][ready]
\_ 19:0:0:0 sdd 8:48 [active][ghost]
\_ 20:0:0:0 sdf 8:80 [active][ghost]
\_ 21:0:0:0 sdh 8:112 [active][ready]
And multipath.conf :
defaults {
udev_dir /dev
polling_interval 5
prio_callout none
rr_min_io 100
max_fds 8192
user_friendly_names yes
path_grouping_policy multibus
default_features "1 fail_if_no_path"
}
blacklist {
device {
vendor "*"
product "Universal Xport"
}
}
devices {
device {
vendor "DELL"
product "MD36xxi"
path_checker rdac
path_selector "round-robin 0"
hardware_handler "1 rdac"
failback immediate
features "2 pg_init_retries 50"
no_path_retry 30
rr_min_io 100
prio_callout "/sbin/mpath_prio_rdac /dev/%n"
}
}
And sessions.
[root@xnode1 dell]# iscsiadm -m session
tcp: [13] 10.0.51.220:3260,1 iqn.1984-05.com.dell:powervault.md3600i.6d4ae520009bd7cc000000004fd7507c
tcp: [14] 10.0.50.221:3260,2 iqn.1984-05.com.dell:powervault.md3600i.6d4ae520009bd7cc000000004fd7507c
tcp: [15] 10.0.51.221:3260,2 iqn.1984-05.com.dell:powervault.md3600i.6d4ae520009bd7cc000000004fd7507c
tcp: [16] 10.0.50.220:3260,1 iqn.1984-05.com.dell:powervault.md3600i.6d4ae520009bd7cc000000004fd7507c
I'm getting very poor read performance :
dd if=/dev/mapper/mpath1 of=/dev/null bs=1M count=1000
The SAN is configured as follows:
CTRL0,PORT0 : 10.0.50.220
CTRL0,PORT1 : 10.0.50.221
CTRL1,PORT0 : 10.0.51.220
CTRL1,PORT1 : 10.0.51.221
And on the host :
IF0 : 10.0.50.1
IF1 : 10.0.51.1
(Dual 10GbE Ethernet Card Intel DA2)
It's connected to a 10gbE switch dedicated for SAN traffic.
My questions being; why the connection is set up as 'ghost' and not 'ready' like an active/active configuration ?
