iscsi or nfs for reliable connection to san/nas?

[gbras]

Hi,

I'm planning to connect an external storage enclosure (based on the Linux Openfiler san/nas sw) to an ESX 3.5 (VI foundation) host.

I need the openfiler nas/san to appear as a scsi disk to an SBS 2003 R2 virtual machine.

Which is the most reliable way to connect it to ESX: nfs or iscsi?

Bot machines will be connected to UPS, but one of my concerns is: what happens if the san/nas goes offline (for a power failure or other cause) and I later reconnect it? Will the SBS 2003 vm go down or lock-up/freeze for this?

Thanks in advance

Guido

[Texiwill]

Hello,

ESX Supports both for the placement of VMs, so that really does not figure well in choosing which is best. I prefer iSCSI myself, but others get NFS to work without a hitch. As for the Windows VM, you have several choices: present an iSCSI RDM to the VM, use an iSCSI Target within the VM (supposed to be faster), or try to get Windows to work with NFS which means you need a NFS Client within your VM.

So in essence the easiest path to take is to use iSCSI as your Windows VM has that support direct from Microsoft.

As for what happens when the network goes down? Unless you have redundant paths from the openfiler server, you loose all connectivity. The VM will report it can not access the disk, etc. Any application you are running within the VM could fail (depends on how the application was coded). But in essence until that storage was brought back up the VM would be crippled. If the VM itself lived on an iSCSI LUN then there is a chance it will ALSO not work very well. Perhaps halt,crash, or Blue Screen. But this is the case with any remote storage that looses its connections to the ESX Server.

Best regards,

Edward L. Haletky

VMware Communities User Moderator

====

Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education. As well as the Virtualization Wiki at http://www.astroarch.com/wiki/index.php/Virtualization

[java_cat33 · Accepted solution]

Hi - I've implemented OpenFiler (iSCSI) and NFS in DEV environments - iSCSI is my preference.

My advice would be to install the Microsoft iSCSI software initiator and let the SBS connect directly to the storage. It's simple and works well.

In the environment I set it up in, I use the ESX sw initiator as the OpenFiler hosts a couple of VMFS luns - no problems.

I also found that iSCSI is a lot faster than NFS - but this also depends on your network and disk speeds etc.

[gbras]

Thanks a lot guys!

Guido