I'm having a few issues with path priorities. It seems that the choice
of path to use during I/O is independent of the user defined priorities
for each path.
I am setting the priorities by executing writing a script that is used
by prio_callout. This seems to work when I execute multipath -ll since
all the specified priorities show up correctly. (the
path_grouping_policy being used is failover)
multipath -ll:
--------------
mpath2 (244534e3833623961) dm-1 DSNET,Dispersed Store
[size=47G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=10][enabled]
\_ 85:0:0:0 sdc 8:32 [active][ready]
\_ round-robin 0 [prio=5][enabled]
\_ 87:0:0:0 sde 8:64 [active][ready]
mpath1 (244534e3266616134) dm-0 DSNET,Dispersed Store
[size=47G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=5][enabled]
\_ 84:0:0:0 sdb 8:16 [active][ready]
\_ round-robin 0 [prio=10][enabled]
\_ 86:0:0:0 sdd 8:48 [active][ready]
At this point when I dd to /dev/mapper/mpath1 or /dev/mapper/mpath2 the
priorities don't come into play at all. Data starts going to /dev/sdc
for /dev/mapper/mpath2 & /dev/sdb for /dev/mapper/mpath1, which totally
by-passes the set priorities. Below is a list of all the conf files and
scripts I'm using.
/etc/multipath.conf
--------------------
defaults {
udev_dir /dev
polling_interval 1
selector "round-robin 0"
path_grouping_policy multibus
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
prio_callout "/bin/bash
/root/MultipathScripts/mpath_prio_alt %n"
path_checker tur
rr_min_io 128
max_fds 8192
rr_weight priorities
failback immediate
no_path_retry queue
user_friendly_names yes
}
/root/MultipathScripts/mpath_prio_alt :
---------------------------------------
#!/bin/bash
# if not passed any device name, return a priority of 0
if [ -z "${1}" ];then
echo 0
exit
fi
ENTRY="$(ls -l1 /dev/disk/by-path | grep /${1}'$')"
DEV="${ENTRY##* ip-}"
if [ "$DEV" = "${ENTRY}" ];then #This is not an iSCSI device
echo 0
exit
fi
# stripping $ENTRY to obtain the IP:Port-iscsi-iqn-lunNumber
DEV="${ENTRY##* ip-}"
#DEV="${DEV%% ->*}" # the pattern changed in CentOS 5.3
#DEV="$(echo ${DEV} | sed 's/-lun-[0-9][0-9]* ->.*//')"
DEV="${DEV%%-lun-[0-9]* ->*}"
echo $(grep ${DEV} /root/MultipathScripts/iscsi.list | cut -f2)
/root/MultipathScripts/iscsi.list:
----------------------------------
192.xxx.xxx.103:3260-iscsi-iqn.2008-07.com.company:stoarge-2 1
192.xxx.xxx.106:3260-iscsi-iqn.2008-07.com.company:stoarge-2 0
192.xxx.xxx.103:3260-iscsi-iqn.2008-07.com.company:stoarge-1 0
192.xxx.xxx.106:3260-iscsi-iqn.2008-07.com.company:stoarge-1 1
Is there something I'm doing wrong? I would like to be able to define
the priorities per device, and ensure that data only traverses on the
lower priority path when
a) a failure to the first path (path with a higher priority) occures
b) no other path with a higher priority exists
--
Akshay Lal
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
