Virtual SAN 6.0 Hardware Requirements

Off lately i have seen a number of people asking for Prerequisite for setting up VSAN cluster from the hardware perspective. Although this information is available in the VSAN 6.0 design and sizing guide , i thought of writing a short and crisp article.

:8-2-2015 10-12-54 PM

– Minimum of 3 hosts in a cluster configuration
– All 3 hosts must contribute storage
– Recommended that hosts are configured with similar hardware
– Hosts: Scales up to 64 nodes
– Disks: Locally-attached disks
– Hybrid: Magnetic disks and flash devices
– All-Flash: Flash devices only

– SAS/SATA/PCI-e SSD {At least one of each}
– SAS/NL-SAS/SATA HDD{At least one of each}
– 1 Gb/10 Gb NIC
– SAS/SATA controllers (RAID controllers must work in “pass-through” or RAID0” mode)
– 4 GB to 8 GB USB, SD Cards
1 GB Ethernet or
10 GB Ethernet (preferred) (required for all-flash)
“Witness” component (only metadata) acts as tie-breaker during availability decisions

Any server which is on VMware Compatibility Guide(VMware Compatibility Guide > Virtual SAN  ) can be used to setup the VSAN Cluster.

VSAN Cluster can be set in either Hybrid configuration or in all flash configuration .

VSAN Hybrid configuration:

– In Virtual SAN hybrid, all read and write operations always go directly to the Flash tier
– Flash-based devices serve two purposes in Virtual SAN hybrid architecture
– Non-volatile write buffer (30%) {Writes are acknowledged when they enter prepare stage on the flash-based devices}

– Read cache (70%) {Cache hits reduce read latency}
– Cache miss – retrieves data from the magnetic devices

VSAN All Flash configuration:

– In Virtual SAN all-flash, read and write operations always go directly to the Flash devices
– Flash-based devices serve two purposes in Virtual SAN all-flash
– Cache tier (write buffer) { it is recommended to use High endurance flash devices in cache tier}
– Capacity tier {Low endurance flash devices}

Magnetic Disks (HDD)

– SAS/NL-SAS/SATA HDDs supported
– 7200 RPM for capacity
– 10,000 RPM balance between capacity and performance
– 15,000 RPM for additional performance

– NL SAS will provide higher HDD controller queue depth at same drive rotational speed and similar price point
NL SAS recommended if choosing between SATA and NL SAS

Storage Controllers:

– SAS/SATA storage controllers
– Pass-through or “RAID0” mode supported
– Performance using pass-through mode is controller dependent
– Check with your vendor for PCI-e device performance behind a RAID-controller
– Replacing devices for upgrade of failure purposes might require host downtime
– Support for hot-plug devices
– Storage controller queue depth matters
– Higher storage controller queue depth will increase performance
– Minimum queue support of 256
– Validate number of drives supported for each controller


1 Gb / 10 Gb supported for hybrid architecture
– 10 Gb shared with NetIOC for QoS is recommended for most environments
–  If 1 GB, recommend dedicated links for Virtual SAN
10 Gb supported only for all-flash architecture
– 10 Gb shared with NIOC for QoS will support most environments
Jumbo frames will provide nominal performance increase
– Enable for greenfield deployments
– Enable in large deployments to reduce CPU overhead
Virtual SAN supports both VMware vSphere standard switch and VMware vSphere Distributed Switch™ products
– NetIOC requires VDS
Network bandwidth performance has more impact on host evacuation and rebuild times than on workload performance

Firewall Ports:

Virtual SAN Vendor Provider (VSANVP)
– Inbound and outbound – TCP 8080

Virtual SAN Clustering Service (CMMDS)
– Inbound and outbound UDP 12345 – 23451

Virtual SAN Transport (RDT)
– Inbound and outbound – TCP 2233

Hope this post was useful . more info here:

Click to access VSAN_Design_and_Sizing_Guide.pdf

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