Open a Vm in a san on 2 different esx hosts

[Giampos17970]

Hi, I have a Vsphere essential, 2 Esx hosts and a Iscsi san, I need to link the Vm in both esx host (i know I haven't FT and HA), in order to run the Vm ever in the first Esx, and in case of first host fails, to run the Vm on the second esx.

I tryied to link the Vm to the second host, but Vsphere client tell me that's not possible, because the Vm is already present at the first ESX.

There's a way to prepare this setting?

[FranckRookie]

Hi Giampos17970,

As the VM is already in the vCenter database, it is not possible to register it a second time. But you don't need it in fact. In case the first ESX crashes, you just nee to restart the VM from the other host as it can see the VM on the shared storage.

Hope it helps.

Regards

Franck

[kashifsajjad]

SOLUTION 01

1) Powered off the VMNodeA that you want to run on other Host incase of Failure.

2) Create a New VMNodeB on 2nd Host and Map Hard Disk of VMNodeA to VMNodeB

3) Power ON VMNodeA on Host-A. if Host-A fails or Down then Start VMNodeB as Both have Same Hard Disk with Same Settings Hope it Will Work.

SOLUTION 02

there might be a chance that after VMNodeA shutdown abnormally, VM may be locked for sometime. to avoid this you may use thick disk which can be used to Share same hard disk by two or more VM's while they are running

1)Create a share disk to be used byboth VM'. Suppose you iSCSI data Store name is "iscsistore01"

2) Login to your ESX Console and type the command for creating share disk of 30 GB size

#vmkfstools –c 30G –d eagerzeroedthick –a lsilogic vmfs/volumes/iscsistore01/shareddisk01.vmdk

3) Start with VMNodeA by going to VM > Edit Settings and click the Add.. button and select Hard Disk from the device listing. Click Next.

4) On the Select a disk page, choose the radio button, Use an existing disk and Click Next.

5) Browse to the location of the shared disk, select it and click Next.

6) On the Specify Advanced Options page, choose a new SCSI device node. The shared disk must reside on a different SCSI controller. Use SCSI(1:0), for

example. Click Next, then Finish.

6. Now select the newly added SCSI controller. For the SCSI Bus Sharing, choose Virtual, then click Ok.

USE SAME SETTING ON VMNodeB

Power ON VMNodeA registered on ESX-A and incase if ESX-A will fail to start or down Power on VMNodeB registered on ESX-02

[jcwuerfl · Accepted solution]

So some of this may depend on your applicaiton, if you can run multiple instances of the same application? If its a web application? Does it store its data in files on the server or does it store it in a database locally? or remote database?

- VM on local storage of the Host, wouldn't really be recommended if you need to startup the VM on hostB quickly.

- If both Hosts have access to the same storage lets say and if the application can really only be run once. You could only register it to HostA and if that fails at some point it will release the lock it has on the VM and you will be able to manually register the VM to hostB, and startup the VM. However, you won't be able to really do this ahead of time.

- HA sort of here as if a Host fails or power goes out on HostA, HostB will power the VM back down automatically

- FT - about here in the spectrum creates a ghost VM on the secondary host in lock-step (everything that happends on HostA happens on HostB)

- Another option on the other end of things is setting up Microsoft Clustering using MSCS as that does support iSCSI I believe. You can run to VM's with iSCSI to your SAN and cluster the application that way. Just note that with client iscsi it does use some CPU to create the iscsi packets.

- Web Cluster, Database Cluster. Doesn't matter if one of the web server nodes or database nodes go down really as the user would get redirected to another node in the cluster thus really no need for HA/FT.

Of course with some of the above there are costs and pro's / con's and are some ways to increase uptime.