Monday, February 3, 2014

Nimble Scale-Out - The Curtain is Drawn - Part II - What's a Group? - Part II (How Many Parts Do We Got In This Thing?)

Okay, okay, all of these Part #, Part # are probably really annoying, but I realized after reading my blog that I left some things out that I really wanted to tell you about regarding groups.  So instead of trying to tack on extra stuff to the original article, yada, yada, yada, you get it.

If you didn't notice there's a lot of cool new stuff to 2.x, but there are some caveats to be aware of.  Nothing Earth shattering, but stuff I feel you should be armed with before you jump head first into the deep end of 2.x.

Okay, so let's quickly go over the benefits of 2.x.

1.  4 array GUI's in 1. (Ease of administration!)
2.  Add new arrays to the group as you purchase new hardware.
3.  Remove old hardware with no downtime as they retire.

So somethings to watch out for when going to 2.x.
1.  Networking.  Yep, we covered this in the previous blog post.
2.  Volumes.  Source groups vs. Destination groups.
3.  DR and replication.

Let's talk about 2.  The Source group is the group or array that's going to merge into the Destination group.  We covered this a little bit, that the Source will lose most of it's identity, when it joins the Destination.  Now if this is a new array, NO problem, but what if it's an existing array with volumes and data being served?  If it has data and volumes, those volumes have to be temporarily taken offline while the array/Source joins the Destination.  Not a huge issue, but something to keep in mind if your Source already has data on it.

How about 3.  Similar to number 2, replication needs to be paused during the merge.  But something more to think about is if you happen to be replicating between the Source array and Destination array, that won't work anymore with arrays in the same group.  Again, not Earth shattering, but something to keep in mind if you're implementing this at your site.

Now what happens if you realize the gated community is just not for you?  The neighborhood kids pee in the pool and the rules are too strict.  Can you pick up your array and leave?  You sure can!  Again there are caveats and you'll need to migrate shared volumes, snapshots, clones, etc.  But, all joking aside this is a VERY cool feature when you've got an older array in your group that you're looking to either retire or turn into a DR array.

Until Next Time!

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