Simplivity | RAID | RAIN

[MrIndiaPST]

Do HPE Simplivity nodes use RAID and RAIN protection while vSAN only uses RAIN.

[Sanika]

Hello @MrIndiaPST ,

Yes, in order to ensure data resilience and data availability, HPE SimpliVity nodes use both RAID and RAIN protection. The Data Virtualization Platform (DVP) is used by HPE SimpliVity for data protection, which includes RAIN technology.
The combination of RAID and RAIN within the HPE SimpliVity platform allows us to provide extremely high levels of data protection in as few as two nodes (and also provide full RAID data protection on even a single node).

vSAN employs RAIN as its sole data protection mechanism relying on its distributed architecture for redundancy. It doesn't employ traditional RAID within nodes.

You may refer the below video link which explains in detail about RAIN VS RAID in HPE SimpliVity:
https://www.youtube.com/watch?v=EmWtuXXTVGI&ab_channel=vBrownBag

Regards,
Sanika

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[MrIndiaPST]

Hai Sanika,

Thanks,

Is it correct that vSAN use only RAIN

[Sanika]

Hi @MrIndiaPST 

Yes that's correct. vSAN does not use hardware RAID, instead the data is protected at the software layer. vSAN uses a concept of disk groups with a minimum of one disk group required per host.

In vSAN, a form of RAID is implemented but it cannot be called RAID really, as we are not working with disks (the D in RAID). We are working with objects and components of those objects. RAIN protects individual data objects (files, virtual disks) rather entire disks. A more correct term would be RAIN (or Redundant Array of Independent Nodes).
In the vSAN implementation of RAID5, 4 components of the parent vDisk object is created. The data is spread across these components in a manner similar to that of RAID5 in the disk world. To guarantee redundancy, each of the components must be placed on a different host, so a single host failure would take more than one component offline.

For more details on this, you may refer the below links:

https://www.definetomorrow.co.uk/blog/2017/9/18/vmware-vsan-a-closer-look-part-2-architecture-and-hardware#:~:text=Yes%20that's%20correct%20%E2%80%93%20vSAN%20does,disk%20group%20required%20per%20host.

https://communities.vmware.com/t5/VMware-vSAN-Discussions/Why-we-can-t-use-RAID-5-policy-on-3-nodes-vSAN/td-p/1770897

Regards,
Sanika.

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