ISCSI - can't share a lun/volume between 2 hosts ?

[powers]

I have just set up ISCSI SAN with 2 blank volumes.

I've added one of the volumes to server1. It says 418G Free space.

I've then tried to add the same volume to server2 and it says there is no available capacity, and that the current disk layout will be destroyed if I continue.

ISCSI volumes can't be shared between hosts?

I was going to move a VM from server1 to the volume, then browse the datastore and add the vm via right clicking the vmx file

[depping · Accepted solution]

Yes you can. But you don't need to create a new VMFS volume. Just rescan your HBA's on the second server that's all there is to it.

Duncan

VMware Communities User Moderator | VCP | VCDX

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[powers]

ok, so Add storage actually creates a new VMFS volume......

Tried a rescan and it has shown up. Only odd thing is LUN 0 says "enclosure" wheras the other host doesn't show that LUN.

Thanks

[imanage]

I have this setup (8x ESXi Hosts sharing 1x 2TB iSCSI NAS). You need to enable the multi path option on the source iSCSI NAS/SAN. This will allow multiple hosts to read/write to one volume.

[powers]

Thanks for the help - I've awarded points.

[MattZhou]

My $0.02:

iSCSI SAN technology itself does not provide any instruments for handling multiple concurrent read/write requests for many initiators. If you are creating an iSCSI target device and share it over iSCSI in a clustered mode (allowing multiple concurrent iSCSI connections) - you just make it available for many Initiators to access it. This however does not mean that you provide shared access to the data on this iSCSI target. iSCSI itself cannot control multiple requests from the Initiators. Imagine that 3 different heads are writing the data simultaneously onto the same track of the hard drive - there will be a data mess as a result. In order to provide clustering service for iSCSI targets, one can do one of the following: 1. Use VMware ESX and format iSCSI target in vmfs file system (since vmfs is a clustering file system) 2. Use a dedicated clustering file system on your SAN (Data Plow SFS, etc.) or software, allowing NTFS to be used as SAN file system (MetaSAN, or alike)

(Pasted from [http://www.starwindsoftware.com/forums/starwind-f5/trying-clear-this-use-iscsi-instead-smb-t1392.html])