Shared storage on ESXi host

[FenasiKerim]

Hello,

I'm having a bit of a problem configuring shared storage for vMotion and I'd appreciate any help you can provide.

I'm trying to have the following config:

• 2 ESXi 4.1 hosts (e.g. A and B) that'll run VMs.

• 1 ESXi 4.1 host (e.g. C) as shared datastore to keep the VM configs.

• 1 Windows Server 2008 server running vCenter.

Ultimately I'd like to be able to create a shared datastore on C that both A and B can read/write to so I can perform vMotion between A and B.

Is it possible to implement this config with a regular ESXi host running on C? At the moment all the ESXi hosts are bare bone PCs with IDE drives. In other words, I wonder if I can convert a regular ESXi server running on a regular PC to a shared storage host or do I need a dedicated NAS in place of C for that?

Ultimately I would like to initiate vMotion between two ESXi hosts (i.e. A and B) and keep the configuration files on a separate host, preferably another plain ESXi host with a regular IDE drive.

I'm very new to all this so I'd appreciate any pointers.

Regards,

J

[PaulusG · Accepted solution]

Hello and welcome to the forums

I do not know the hardware for ESXi host A and B.

But in a scenario that you want iSCSI storage and vMotion,

at least you need 2 extra NICs per ESXi host (VMotion requires Gigabit)

If you want host C for shared data storage,

- you can go for a VM that does the job (worst scenario)

- Make it a dedicated iSCSI box with OpenFiler (http://www.openfiler.com/) or FreeNAS (http://freenas.org/downloads) (better)

And do some additional reading on this forum about using thes products.

- Buy a seperate Storage box (best)

If BOX C has an IDE drive, performance is not that good

I do not know if you are gooing to run a production environment or just a lab.

In case of production, I would recommend to check the Compatibility, in case of support issues

http://www.vmware.com/resources/compatibility/search.php?q=vmware%20compatibility%20list&aq=0&aqi=g1...

Paul Grevink

Twitter: @PaulGrevink

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[Cyberfed27]

You've got me confused, if you want A&B to be in a VMware cluster, the datastore must be shared by both A&B at the SAN level. That is, both A&B must have access to LUN(s) you have assigned them.

I don't see why you would want to keep "C" out of the cluster.

Create a 3 node cluster in VMware managed by vCenter. On the storage side of the house the LUNS you create and assign to VMware (Datastores) must be accessible by all 3 VM hosts.

[PaulusG]

Hi Cyberfed27,

It is exactly as you have already stated, a cluster needs shared storage (like FC, iSCSI or NFS).

If you use C to provide storage, there is no need to have C in the same cluster.

What do you exactly mean by "shared datastore to keep the VM configs"?

A VM config file, the *.vmx file is just a small file. Most important are the disk files,

that contain the actual data

Do you have some more info about your environment?

Paul Grevink

Twitter: @PaulGrevink

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[FenasiKerim]

Thanks for your answers, really appreciated.

My goal is to test vMotion by moving a running virtual machine from one physical ESXi host (e.g. A) to another (e.g. B) and capture the traffic generated in the network.

I initially started with two ESXi hosts (A and B) and a separate Windows server with vCenter installed. I installed virtual machines on A and B and tried vMotion only to find that the VMs were supposed to reside on a shared datastore that can be seen by both A and B with read/write access for vMotion to work. This brought the machine C into the picture, hoping a simple ESXi installation could provide that 'shared datastore' requirement. (My thinking was ESXi provides MVFS and could be used to expose machine C's harddisk as a shared datastore - remind you I'm completely new to this!) I couldn't manage (not sure if it even makes sense) to use C as my shared datastore, hence my question before I grabbed a NAS which looks like a viable solution.

I'm in the process of installing FreeNAS on machine C at the moment as Paul suggested. I was just hoping to get away with a simple ESXi installation for the shared datastore.

I'm sure I lack the right VMware terminology to better explain it but what I'm trying to come up is a test rig to test vMotion with a total of 4 physical PCs: 2 ESXi hosts running various VMs, 1 'shared storage' machine that can be seen by the 2 ESXi hosts and 1 Windows PC runnig the VCenter.

Thanks for your kind responses, really helps me out. I'll let you know how the FreeNAS adventure goes.

Thanks,

J

[Cyberfed27]

Ok I'm starting to get a better understanding of what you are trying to say. Terminology is a bit off but thats OK!

The third server "server C" which you setup as an ESXi host will not perform the actions of providing shared storage.

VMware doesn't do the shared storage portion, a seperate mechanism must do that which would be a SAN in 99.9% of setups.

It sounds to me like you don't have a SAN, hence the discussion about FreeNAS.

So in your setup you would need to do the following:

Setup server "C" with whatever OS runs FreeNAS (I'm not familiar with FreeNAS). Setup and configure FreeNAS to create and share out a LUN (or whatever FreeNAS may call it) to both servers "A" and "B", both servers A & B must have access to this same storage location.

Then, assuming this is configured correctly, you can go into vCenter and attach that storage LUN to both servers A & B. Essentially a shared datastore.

This will meet the shared storage requirement for vMotion. The only other portion to setup would be the network configuration for vMotion from within vCenter.

[PaulusG]

Hello FenasiKerim,

Your last post made everything clear.

Indeed, the idea of C with VMFS as a shared storage is unfortenately not possible.

A VMFS on a ESX(i) host is always local storage.

Theoratically and practical you can build a VM that offers storage by means of iSCSI

or NFS. Going that way, you have a shared storage (I use that in my homelab)

I am curious why you want to test vMotion. vMotion is the process

of copying memory blocks from one ESX host to another. The amount

of traffic depends on many factors.

Some suggested reading on the subject, a bit old: http://www.vmware.com/pdf/usenix_vmotion.pdf

On this page all documentation: http://www.vmware.com/support/pubs/vs_pages/vsp_pubs_esxi40_i_vc40.html

Suggestions: The Introduction and Getting Started papers

Paul Grevink

Twitter: @PaulGrevink

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