IP failover with Qumulo Core

IN THIS ARTICLE

Outlines how to enable IP Failover in Qumulo Core

REQUIREMENTS

• Cluster running Qumulo Core
• Command line (CLI) tools installed via API & Tools tab

For details on configuring your DNS server to point to the floating IPs, check out the Set Explicit DNS Hostnames and IP Mappings article. 

PROCESS

IP Failover is a high-availability feature that allows a node's virtual IP address(es) to be reassigned to other nodes in the cluster should a node go offline for any reason.

In addition to the fixed IP range assigned to a cluster, an administrator can set a floating range of addresses that can be reshuffled amongst online nodes as necessary. When using IP Failover, it is recommended that the cluster's client-facing DNS record be pointed at these floating IPs as opposed to the fixed range.

Clients mount the cluster using one of the following recommended mount options:

Mac Client

mount -t nfs -o rsize=65536,wsize=65536,intr,hard,tcp,rdirplus,readahead=128 your.qumulo.ip:/share /path/to/mountpoint

Mac Client with Local Locking Enforced

mount -t nfs -o rsize=65536,wsize=65536,intr,hard,tcp,locallocks,rdirplus,readahead=128 your.qumulo.ip:/share /path/to/mountpoint

Linux Client 

• Please note that modern Linux distributions auto negotiate a 1MB read/write block size (rsize/wsize of rsize=1048576).

mount -t nfs -o intr,hard,tcp your.qumulo.ip:/share /path/to/mountpoint

Linux Client with Local Locks Enforced

mount -t nfs -o intr,hard,tcp,local_lock=all your.qumulo.ip:/share /path/to/mountpoint

In a node outage scenario, any IP in the floating range that was assigned to the offline node would move to another available node ensuring that connected clients can continue writing and reading to/from the cluster. Typically the time it takes to fail an IP over to another node will cause only a momentary blip in any running workloads. Please note that certain connections like SMB will have to re-connect, as they require a new TCP connection. However, the failover is fast enough that most operating systems' retry mechanism can handle it.

We recommend assigning enough floating IP addresses so that each node will have the total number of nodes minus one for the number of floating IP addresses per client-facing VLAN. The math to use is (N-1)*N where N is the total number of nodes in the cluster. Assuming many client connections, this best practice could help evenly distribute the connections from the lost node onto the remaining nodes as needed. For example, in a 4 node cluster when 1 node goes offline, its 3 virtual IPs would then float to each of the remaining 3 nodes.

NOTE: The number of floating IPs is dependent on your workflow and clients connecting to the cluster, with a minimum of 2 floating IPs per node per client-facing VLAN, but no more than 10 floating IPs per node per client-facing VLAN or 70 floating IPs per namespace.

Configure IP Failover via the Web UI

1. Log in to your cluster's Web UI as 'admin'.
2. Hover over the Cluster menu and select Network Configuration.
   
   
   
   
3. On the Network Configuration page, click on Edit Static Settings.
   
   
   
   
4. In the fields for Persistent IPv4 Addresses and Floating IPv4 Addresses, enter your fixed and floating ranges.
   
   
   
   
5. Click Save.

Configure IP Failover via the QQ CLI

1. Using a node's IP address, ssh to the cluster as admin.

ssh admin@10.101.1.101

2. Login as root.

sudo -s

3. Run the following qq command replacing the IP range with your preferred floating range.

qq network_conf_mod --floating-ip-ranges 10.100.1.201-204

Once IP failover is configured, confirm that your clients are using the new floating IPs. If a client already has a mount point based on a previous static IP, you will need to unmount and remount the Qumulo cluster, ensuring that the new mount picks up the floating IP set. The DNS record must be updated to list the floating IPs and not the static ones for the cluster before remounting.

RESOLUTION

You should now be able to successfully configure IP failover in Qumulo Core

ADDITIONAL RESOURCES

Recommended NFS Mount Options

Qumulo in AWS: Configure IP Failover

Qumulo in GCP: Configure IP Failover

Set Explicit DNS Hostnames and IP Mappings

QQ CLI: Networks and IP Addresses

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