Forum
Welcome, Guest
Username: Password: Remember me
This is the optional category header for the Suggestion Box.
  • Page:
  • 1
  • 2

TOPIC: HA-Lizard - NoSan 2 Node configuration

HA-Lizard - NoSan 2 Node configuration 11 months 2 weeks ago #1683

  • Salvatore Costantino
  • Salvatore Costantino's Avatar
  • Offline
  • Posts: 593

Situation 1) is clear what happens in case of failure of the host my question is: what should I do once the host is repaired-restored? Do I have simply to reboot the host? Let's assume that the master node fails and that it stays down for 4 days, which are the actions we should put in place? In terms of Xen serve, if i do not force the promotion of the other node as a master it will be available again, my worries are related to the storage replica.

A failed host will rejoin the pool with no user intervention. Should the master rejoin the pool, it will demote itself to slave automatically. Also, replication will automatically start and bring the newly joined host up to date. With that said, depending on the nature of the event that caused the failure, it is possible (but rare) that DRBD could be in a split brain situation. In this case, the host still rejoins the pool and storage is fully available to both hosts, however, replication will be paused. An email alert will be triggered should this occur. Also, there is a script bundled with iscsi-ha that you can run to clear DRBD split brain and restart replication. You can find it here? /etc/iscsi-ha/scripts/drbd-sb-tool

The script is a sort of wizard that asks a few questions and makes the process easy.

Situation 2: Same doubt as before, what should I do once the connection is restored and, furthermore, It's not really clear your idea of 2 heuristic ip? Is this a parameters I can set up manually? If i remember properly the wizard ask for a single heuristic IP but the logic you explained would be really useful.


You are correct, the script only asks for a single IP. You can, however, configure multiple IPs. In the case of multiple, the surviving host MUST reach all of the IPs in the list in order to count as 1 vote which is needed to recover the pool. It makes recovery more restrictive and more prone to the pool shutting itself down in certain situations.

After the script installation is completed, you can tweak any of the changes from the CLI. All settings are documented in the HA-lizard admin guide. You can also type "ha-cfg" with no arguments for a list of available commands or "ha-cfg help" for a detailed description of all settings.

To change the heuristic IP , use "ha-cfg set fence_heuristics_ips x.x.x.x:x.x.x.x:x.x.x.x", using a colon to separate the IPs in the list.

Please Log in or Create an account to join the conversation.

HA-Lizard - NoSan 2 Node configuration 11 months 2 weeks ago #1684

  • Salvatore Costantino
  • Salvatore Costantino's Avatar
  • Offline
  • Posts: 593

One more question, i forgot to mention it before.
The servers we have to work with are built with a set of two little ssd raid 1 (used for the installation of the OS) and a huge RAID5.
I don't know if the Xen installation wizard will distinguish the two storages permitting me to assign the huge one to "Local Storage" or if I have to introduce the huge one later on.
I do think that the script will recognize also a storage introduced after the installation and whose name is not Local storage, am I right?


When installing XenServer or XCP, the installer will ask which storage is to be used for VM storage. If you have more than 1 storage (as you do) it is important to select only 1 and leave the second larger storage deselected. If you select both, XenServer will create a Volume Group which spans both sets of storage which is messy in my opinion. Also, our installer is not able to deal with this situation.

When running our installer, you will then have to manually set the storage for HA-Lizard. In this case, do not allow the installer to convert local storage. Instead manually set the path to the block device. In your case, it will likely be something like /dev/sdb.

Please Log in or Create an account to join the conversation.

HA-Lizard - NoSan 2 Node configuration 11 months 2 weeks ago #1685

  • Giorgio Catena
  • Giorgio Catena's Avatar Topic Author
  • Offline
  • Posts: 21
Hi Salvatore,
thanks for the fast replies. I'll keep in mind your indications, I already spoke with my colleague to provide a secondary 10GB nic with spf module in order to have one link with direct connection and a standard cooper connection which will pass through switches.
I will place updates once we have the ok to proceed with the project.
Kind regards.

Giorgio

Please Log in or Create an account to join the conversation.

  • Page:
  • 1
  • 2