iSCSI multipath issue
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.
On Tue, Jul 28, 2020 at 8:56 AM Nick Kas via Users <users@ovirt.org> wrote:
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.
maybe /var/log/vdsm/vdsm.log could tell more.
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
you are mixing "--target" with "--type", should be: iscsiadm --mode discovery --type sendtargets --portal 172.27.0.55 --interface default
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. _______________________________________________ Users mailing list -- users@ovirt.org To unsubscribe send an email to users-leave@ovirt.org Privacy Statement: https://www.ovirt.org/privacy-policy.html oVirt Code of Conduct: https://www.ovirt.org/community/about/community-guidelines/ List Archives: https://lists.ovirt.org/archives/list/users@ovirt.org/message/N5DNXQ5MAMPXMA...
Argh! thanks for the tip about the iscsiadm command. I can discover targets now. I will enable multipathing again and take abetter look on vdsm.log to see what I can find out, will the thread posted.
Just to give an update, iSCSI has been running stably for the past 1+ months. I could only get a stable multipath when I create two multipaths, one for network 172.27.0.x and one for 172.27.1.x, with their respective targets (2 per network). The previous approach of a single multipath with all the networks and all targets was not working, and I could understand why from the logs. or even from the command line of a host. Not sure what the recommended approach really is, and could not find much in the internet about it. If someone has any information or guide to enlighten us as to how multipath should be configured and what are the different options I would appreciate it.
participants (2)
-
Amit Bawer -
Nick Kas