General recommendations for stretched vSphere HA Cluster aka Metro Cluster Storage (vMSC)

This is just a brief blog post with general recommendations for VMware vSphere Metro Cluster Storage (aka vMSC). For more holistic view, please read white paper "VMware vSphere Metro Storage Cluster Recommended Practices"

vSphere HA Cluster Recommended Configuration Settings:

• Set Admission Control - Failover capacity by defining percentage of the cluster (50% for CPU and Memory)
• Set Host Isolation Response - Power Off and Restart VMs
• Specify multiple host isolation addresses - Advanced configuration option das.isolationaddressX
• Disable default gateway as host isolation address - Advanced configuration option das.useDefaultIsolationAddress=false
• Change the default settings of vSphere HA and configure it to Respect VM to Host affinity rules during failover - Advanced configuration option das.respectVmHostSoftAffinityRules=true
• The minimum number of heartbeat datastores is two and the maximum is five. VMware recommends increasing the number of heartbeat datastores from two to four in a stretched cluster environment Advanced configuration option das.heartbeatDsPerHost=4
• VMware recommends using "Select any of the cluster datastores taking into account my preferences" for heartbeat datastores and choose two datastores (active distributed volumes/LUNs) on each site. 
• PDL and APD considerations depends on stretched cluster mode (uniform/non-uniform). However, VMware recommends to configure PDL/APD responses therefore VM Component Protection (VMCP) must be enabled and response should be set to "Power Off and Restart VMs - Conservative". Detail configuration should be discussed with particular storage vendor. 

vSphere DRS Recommended Configuration Settings:

• DRS mode - Fully automated
• Use DRS VM/Host rules to set VM per site locality
• Use DRS "Should Rules" and avoid the use of "Must Rules"

SIOC/SDRS

• Based on KB 2042596 SIOC is not supported
• Based on KB 2042596 SDRS is only supported when the IO Metric function is disabled.

Distributed (stretched) Storage Recommendations:

• Always consult your configuration with your storage vendor
• VMware highly recommends to use storage witness (aka arbitrator, tie-braker, etc.) in third site.

Custom automation for compliance check and / or operational procedures Recommendations:

• VMware recommends manually defining “sites” by creating a group of hosts that belong to a site and then adding VMs to these sites based on the affinity of the datastore on which they are provisioned. 
• VMware recommends automating the process of defining site affinity by using tools such as VMware vCenter OrchestratorTM or VMware vSphere PowerCLITM. 
• If automating the process is not an option, use of a generic naming convention is recommended to simplify the creation of these groups. 
• VMware recommends that these groups be validated on a regular basis to ensure that all VMs belong to the group with the correct site affinity.

Other relevant references:

1. VMware vSphere Metro Storage Cluster Recommended Practices
2. Setting Multiple Isolation Response Addresses for VMware High Availability (1002117)
3. vSphere HA respecting VM-Host should rules?
4. Using EMC VMAX Storage in VMware vSphere Environments

Galera Cluster for MySQL vs MySQL (NDB) Cluster

In the past, I used to use MySQL database for lot of projects so I was really interested what is the progress in MySQL clustering technologies and what is possible today. Therefore I have attended very interesting webinar  about MySQL clustering possibilities. Official webinar name is "Galera Cluster for MySQL vs MySQL (NDB) Cluster. A High Level Comparison" and Webinar Replay & Slides are available online  here.

I was very impressed what is possible today and even I moved from software architecture and development to datacenter infrastructure architecture and consulting it is good to know what database clustering is available nowadays.