VVSet and Vlun

[kisalipa]

Hi Friends,

I have 2 Hosts

Host A - 8 Vvol exported (lun 0-7)

Host B - 8 Vvol exported (lun 0-7)

Host A and B have 4 Vvols in sharing (lun 4-7)

Now I have created a HostSet AB.

1) What is the best way to present the 4 shared disks to the HostSet?
2) Since the shared disks are already exported to Host A and B individually, why there is need of HostSet
3) In this scenario, where does the VVset fit in? I am confused on this VVset and its usage.

Thanks in Advance!

[Nitesh_123]

Hello @kisalipa

Please find below the link to the HPE 3PAR StoreServ Storage Concepts Guide:

https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c04204225

Kindly refer to the same for information on VVSet and HostSet.

If this helps to resolve your issue, please click the thumb to register a Kudo and mark it as an Accepted Solution.

Thanks and Regards,

@Nitesh_123

[Sheldon Smith · Accepted solution]

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Yes, the HPE 3PAR StoreServ Storage Concepts Guide explains this.

1) What is the best way to present the 4 shared disks to the HostSet?
Stop application(s), unmount and unexport volumes from the individual hosts. Then export the volumes to the HostSet instead, re-mount and resume applications.

2) Since the shared disks are already exported to Host A and B individually, why there is need of HostSet
There isn't a need. It's a simplification of the administration process. By definition, a volume exported to a HostSet is going to all hosts in that set using the same LUN numbers on each host. No concern of forgetting to export a volume to an individual host. And if and when you want to add Host C, you simply add Host C to the HostSet. Any volumes already exported to the HostSet are all instantly exported to Host C.

3) In this scenario, where does the VVset fit in? I am confused on this VVset and its usage.
Again, there isn't a need.  And again, it's a simplification of the administration process. By definition, all volumes of a VolumeSet are exported to a host(s) as a contiguous group of LUNs. Add the volumes in desired order to the VolumeSet and export. Those volumes will be in that LUN order on (each) host. If you add a volume to the VolumeSet later, it will be instantly exported to all hosts as the next LUN number in the LUN sequence.

Note that If you later might add other volumes outside of the VolumeSet, be sure to explicitly use a higher LUN number to keep some adjacent LUNs vacant for any expansion of the VolumeSet (additional volumes added to the Volume Set).

[kisalipa]

Wow! Awesome explanation. Thanks a lot Sheldon. I am new to HPE 3Par and trying to understand in detail about basics (CPG, LD etc). Your answers are very explanatory and easy to understand. Thanks again!!