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Re: BC License ???

 
Uwe Zessin
Honored Contributor

Re: BC License ???

If you present the original vdisk to the backup server in addition to the production server, you WILL CAUSE DATA CORRUPTION!!

** DON'T DO THAT. **

Many file systems cannot be shared concurrently between two servers.
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Sheldon Smith
HPE Pro

Re: BC License ???

If you present the original Vdisk to a backup server, then your production must be down while the original Vdisk is GONE. Production stays down until you unpresent the Original Vdisk from the backup server and present it back to the original server.

If you present the original Vdisk to a second (or additional) server that is not clustered with the first one(s), the original Vdisk WILL be corrupted.

Scroll up and re-read my reply about "The EVA is not a file server...".

Note: While I am an HPE Employee, all of my comments (whether noted or not), are my own and are not any official representation of the company

Accept or Kudo

Azadeh
Advisor

Re: BC License ???

If I can't present one Vdisk to two or three server simultaneously, then for VMware Machine, we can't have HA ( High availability) because, for example my two Host have see a shared storage which presented to both of them and then we cane define HA . So in this case we have encountered your mentioned problem !!

I have 3 Host for VMware, and I presented some Vdisks to 3 of them as a shared storage ! How is it possible ?
Regards
Sheldon Smith
HPE Pro

Re: BC License ???

As I understand it, the vCenter Server software provides the clustering between the Servers, allowing them to share vdisks for the guest OSes.

Note: While I am an HPE Employee, all of my comments (whether noted or not), are my own and are not any official representation of the company

Accept or Kudo

Uwe Zessin
Honored Contributor

Re: BC License ???

Azadeh, you can present an EVA Virtual Disk to multiple ESX servers, because VMFS3 is a shared filesystem - thought you're using Windows or Linux.


> vCenter Server software provides the clustering

Sorry, but that is not correct (with my definition of file system 'clustering'). VMFS volume consistency is ensured, because each VMFS driver serializes meta-data updates with SCSI reservations. That works completely independend from a vCenter server.


Are we talking about EVA Virtual Disks or Virtual Machine VMDK container files? The latter cannot be shared among VMs.
You need to use Raw Device Mappings (RDMs) *and* a shared filesystem with the guest OSes (no NTFS / Linux extN)
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Steven Clementi
Honored Contributor

Re: BC License ???

"I have 3 Host for VMware, and I presented some Vdisks to 3 of them as a shared storage ! How is it possible ?"


vmfs and ESX in general operates as a clustered file system.



"As I understand it, the vCenter Server software provides the clustering between the Servers, allowing them to share vdisks for the guest OSes."

vCenter has nothing to do with the cluster except to initially set up clustering and manage the environment. Once the cluster is configured, you can theoretically remove the vCenter server, and most everything will continue to run. Sure, there will be a few features that 'pause' cause they use vCenter to operate, but an HA cluster does not need vCenter to "operate" properly.




Steven
Steven Clementi
HP Master ASE, Storage, Servers, and Clustering
MCSE (NT 4.0, W2K, W2K3)
VCP (ESX2, Vi3, vSphere4, vSphere5, vSphere 6.x)
RHCE
NPP3 (Nutanix Platform Professional)