Hello:
I have a system with 2 paths to the SAN which is HITACHI HP. The output of multipath -ll is:
mpath2 (360060e8005491000000049100000700a) dm-1 HP,OPEN-V
[size=10G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=2][active]
\_ 3:0:0:1 sdc 8:32 [active][ready]
\_ 4:0:0:1 sde 8:64 [active][ready]
mpath1 (360060e80054910000000491000007003) dm-0 HP,OPEN-V
[size=10G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=2][active]
\_ 3:0:0:0 sdb 8:16 [active][ready]
\_ 4:0:0:0 sdd 8:48 [active][ready]
If I run multipathd -k and do show config, there is a lot of out put but I think the key things are:
defaults {
verbosity 2
polling_interval 10
path_grouping_policy multibus
failback 5
rr_min_io 10
no_path_retry 5
user_friendly_names yes
bindings_file /etc/multipath.bindings
}
devices {
LOTS OF DEVICE ENTRIES.
device {
vendor (HITACHI|HP)
product OPEN-.*
path_checker tur
failback immediate
no_path_retry 12
rr_min_io 1000
}
}
The device entry for the SAN has rr_min_io set to 1000. I added rr_min_io 10 in the default, but per the man page for multipath.conf entries in the defaults will only be used if they do not appear other places.
Q1) If I want to over ride the rr_min_io value in the devices/device section can I just add a devices/device section in /etc./multipath.conf with the things I want to change or do I have to duplicate everything that is in the built-in devices/device entry?
Q2) How can I determine the best value for rr_min_io?
I assume whom ever added the HITACHI|HP devices/device built-in entry decide on the value
of 1000 for a reason. Maybe they did benchmarks or maybe they just copied another entry
that was some what like what they needed and changed the vendor and product.
I am sure I will have more questions depending on the answers I get to these questions.
-----
Jack Allen
-- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
