Hello evryone,
setup ovirt 4.4.1 on CentOS 8.2 as an experiment, and I am trying to get an iSCSI domain
working but have issues. The little experimental cluster has 3 hosts. There is an
ovirtmgmt network on the default vlan, and two iSCSI network (172.27.0/1.X) with vlans
20/21. ovirtmgmt has all the functions (Data, display, migration etc), and the iSCSI
networks nothing yet, and they are not set as required.
The SAN device is already serving a few iSCSI volumes to a vmware cluster, so I know
things are fine on this end. It has two controllers, and four NICs per controller so a
total of 8 NICs, half of the NICS per controller on 172.27.0.X and half on 172.27.1.X.
When I create the iSCSI domain, I login to only one of the targets, and add the Volume,
all is good and I can use the disc fine.
However when I login to more than one of the targets, then I start having issues with the
Volume. Even when I enabled multipath in the cluster, and I created a single multipath by
selecting both of the 172.27.0/1.X networks, and all the targets, the end result was the
same. The hosts have difficulty accessing the volume, they may even swing between
'non-operational' and 'up' if I transfer data to the volume. When I ssh to
the hosts and i check things in the command line I also get inconsistent results between
hosts, and blocks that appear with lsblk when I first setup iSCSI have dissapeared after I
try to actively use the volume.
I am new to iSCSI so I am not sure how to debug this. I am not sure if my multipath
configuration is correct or not. The documentation on this part was not very detailed. I
also tried to remove the domain, and try to experiment with mounting the iSCSI volume from
the command line, but I cannot even discover the target from the command line, which is
very bizarre. The command
iscsiadm --mode discovery --target sendtargets --portal 172.27.0.55 --discover
returns the message 'iscsiadm: cannot make connection to 172.27.0.55: No route to
host'. Yet through ovirt, and if I select only one target, everything work fine!
Any suggestions on how to start debugging this would really be appreciated.