My Hitachi AMS200 is an Active/Passive array says Hitachi.
By looking at asm13 I see all my paths active. Did use the
"path_grouping_policy multibus" when creating that alias.
The LUNs that are picked up and not aliased in /etc/multipath.conf seem
to show an active/passive setup.
Wondering "How" the [active] or [active] [enables] setup is figured out
by multipath.
(this is a different machine, but with no alias I [active] & [enabled]
path.
mpath5 (1HITACHI_D60090910036) dm-10 HITACHI,DF600F
[size=5.5G][features=0][hwhandler=0]
\_ round-robin 0 [prio=0][active]
\_ 0:0:1:36 sdq 65:0 [active][undef]
\_ round-robin 0 [prio=0][enabled]
\_ 0:0:0:36 sdf 8:80 [active][undef]
This one was aliased with below settings in /etc/multipath.conf
Multipath -l
asm13 (1HITACHI_730600240012) dm-53 HITACHI,DF600F
[size=64G][features=0][hwhandler=0]
\_ round-robin 0 [prio=0][active]
\_ 0:0:1:12 sdba 67:64 [active][undef]
\_ 1:0:0:12 sdco 69:192 [active][undef]
\_ 1:0:1:12 sdec 128:64 [active][undef]
\_ 0:0:0:12 sdm 8:192 [active][undef]
>From /etc/multipath.conf:
multipath {
wwid 1HITACHI_730600240012
alias asm13
path_grouping_policy multibus
path_checker readsector0
path_selector "round-robin 0"
failback immediate
}
>From /etc/multipath.conf:
defaults {
udev_dir /dev
polling_interval 10
selector "round-robin 0"
path_grouping_policy multibus
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_name yes
}
Craig
-----Original Message-----
From: dm-devel-bounces@xxxxxxxxxx [mailto:dm-devel-bounces@xxxxxxxxxx]
On Behalf Of Craig Simpson
Sent: Wednesday, May 21, 2008 7:48 AM
To: device-mapper development
Subject: Round Robin vs Active/Passive
For multipathd and dm is round-robin the only mode for multipathing? The
array we have as a newer Hitachi AMS200 and Active/Passive says the
documentation.
Using round-robin seems to work fine with it. Have 4 paths and they are
all sharing 1/4 of the load.
Are there other options that can be set in /etc/multipath.conf? I only
know of round-robin.
Craig
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