By Pranay Jha
| Apr 19, 2016 | In Articles
| Update: Apr 22, 2017
| Total Views [ 902 ]
Overview of VSAN:-
- VSAN pools the locally attached storage from members of a VSAN–enabled cluster and presents the aggregated pool back to all hosts within the cluster.
- It has multiple disks presented to multiple hosts
- VSAN does not require any additional software installations.
- It is built directly into ESXi itself. Managed from vCenter Server.
- VSAN is compatible with all the other cluster features that vSphere offers, such as vMotion, HA, and DRS.
- We can even use Storage DRS to migrate VMs on or off a VSAN datastore.
- VSAN uses the disks directly attached to the ESXi hosts and is simple to set up.
- VSAN uses the concept calling RAIN, or reliable array of independent nodes.
- VSAN uses a combination of vSphere APIs for Storage Awareness (VASA) and storage policies to ensure that VMs are located on more than one disk and/or host to achieve their performance and availability requirements.
- VMware recommends 10 Gbps networking between ESXi hosts when using VSAN.
Requirements for VSAN:-
- ESXi 5.5 or newer hosts
- vCenter 5.5 or newer
- One or more SSDs per host
- One or more HDDs per host for hybrid mode
- Storage controllers must be on the VSAN HCL
- Minimum of three hosts per VSAN cluster
- Maximum of 64 hosts per VSAN cluster
- 1 Gbps network between hosts (10 Gbps highly recommended)
Types of VSAN Configuration
- All SSD(Flash Only Disconnect)
It uses both SSD and magnetic hard disks.
VSAN requires at least one flash-based device in
Hybrid VSANs use the SSD as a read and write cache just as some external SANs do.
W hen blocks are written to the underlying datastore, they are written to the SSDs first, and later the data can be relocated to the (spinning) HDDs.
VSAN’s read/write cache ratio is 70 percent read, 30 percent write.
It uses all SSD Disks.
Source: Scott Lowe's Mastering vSphere 6.0
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