Thursday, January 30, 2014

Nimble Scale-Out - The Curtain is Drawn - Part II - What's a Group?

Hi Friends,

Today I'm going to go into a bit more depth when adding 2.x arrays to an existing 2.x group.  Remember I showed you how easy it was and I said, "Well, it's a little more involved then that."?  Today I thought I'd show you what's involved and maybe some other bits.

So if you're upgrading a 1.x array to a 2.x array you need to start thinking about your network.  Since this is going to be a cluster some of the individuality that you had with 1.x will be lost when you upgrade to 2.x and join a group.  Now I just used the word "group" a couple of times, and you're probably thinking, "Okay, what's a group?"  Well, it's just that, it's a bunch of arrays(up to 4) joined together to form a group.  And once an array joins a group, it gets all the rights and privileges an array gets at this point.  It's kind of like moving into a fancy gated community.

Sounds pretty exciting eh?  So how does an array get ready to join this exclusive club?  Just like in real life, networking my friends!

Let's take a look at this networking GUI.  I've already added "whenyou" to the same group "wenster" belonged to.  If you haven't guessed it yet, these were named by my buddy Wendel. :-)  Now take a look "iSCSI Host Connection Method".  This is new concept if you've only worked with 1.x.  If you upgrade an array from 1.x to 2.x most likely it will have "Manual" and "Enable rebalancing" not selected.  If you want that array to remain a separate entity, that's okay, just leave it alone.  It can happily live out it's life being a loner and serving up data as a 2.x array without ever being part of a group.  But if you want to live in the fancy community with the dog park and the swimming pool you're going to need the networking and learn to work with others.

Also notice the "Virtual Target IP", another new concept.  Now that you're networking with others, you need an easy way for data to get from point A to B.  I still have data IP's for "wenster" and "whenyou", but now the Virtual Target IP helps sort what data needs to go where automatically!  I know what you're thinking, "How do you keep data from going over the wrong pipes?"  That's an EXCELLENT question!  And all I'm going to say is Nimble's got you covered!  I'll probably write about that in a day or two.  I will say when you populate a group, you're going to want to switch from "Manual" to "Automatic" and select the "Enable rebalancing".

Now, back to networking.  Remember I said that before you start adding arrays to group, think about networking and here's why.

When you try to add an array to a group the array going to try and keep you from making any mistakes.  Pay particular attention to bullets 1, 2, 3, oh heck just read them all!  We wouldn't put them there if they weren't important.  Remember, don't be like Neil and not read the pop ups, they're not there to just annoy you.

Done reading the bullets?  So what we've got is two arrays, "wenster" and "whenyou" and both now belong to a group called "hulk."  Hulk will now take over much of the network identity of the new array that's been added.  Is there a downside to this?  No, not really, BUT you need to remember to prepare for the changes.  It's all about the networking my friends!

So after you've clicked Finish with out reading any of the bullets you will hopefully get this message box.  What!  Wait a second, go back and read those bullet points!

As stated in the earlier bullet points, you'll reconfigure your applications to use the "hulk" or group target IP address and the management of the individual arrays is handled by the group management IP address.

You've just taken the first step to a bright and brand new world.  It's like in the Wizard of Oz where it goes from black and white to color.  Black and white is cool, nothing wrong with it, but WOW what a difference the world looks like in color!

Until Next Time

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