Tuesday, June 28, 2011

Vmware ESXi + FreeNAS = Zombie

Since I don't have access to the newest pictures to update the three sisters garden progress, I decided to Blog about my recent experiment to see what happens when you kill FreeNAS. (Geek alert!!! This is a geeky post I am not responsible for resulting glazed eyes or bewilderment. Read on at your own risk).

I do a fair amount of work with Virtualization. I am responsible for (among many other things) a vSphere environment at work. I have been fiddling with VMware products since very nearly the beginning. I have even brought VMware home, in the form of two ESXi servers, which host a number of my mad experiments. Not long ago, I decided to throw FreeNAS into the mix.

FreeNAS is a specialty server implementation, which allows you to turn a computer and its disk space into a Network Attached Storage device. It is an incredibly flexible and capable, Open Source Application.  I configured it as an iSCSI target, which the ESXi hosts connect to. It was fairly easy to set up (documentation could have been a bit better perhaps...), and has been running a test file server for a couple weeks now. The test file server was located on two datastores, both hosted by the FreeNAS server.

I have been wanting to see what would happen if I pulled the plug on the FreeNAS server, and tonight seemed a good night to stage an untimely death. First I initiated a remote session to the test file server, and ran a ping against it, so I could observe how the virtual machine (which relies on the FreeNAS server) would handle having the world ripped out from under it.

Then I yanked the power cord. The FreeNAS server, of course ceased to exist- black screen, no blinking lights, no merry hum of fans or drives. I went over to my workstation to check on the file server, expecting to see a somewhat less quiet death. Ping was still running. The remote session was still there. Hmm... Not nearly as exciting as I expected. I opened an explorer window on the test file server. it couldn't access its hard drives, including the drive which was hosting the OS. So, its brain was more or less missing, and it was more or less still there. Fascinating! An undead virtual computer!

So, what would happen if I brought FreeNAS back? I plugged it back in, and it dutifully came back to life. The test file server could see it's drives again, and kept on going about its business as though nothing had happened.

While I certainly wouldn't recommend depending upon this as your disaster recovery strategy, I do have to say It was pretty impressive for a bunch of free stuff.

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