EMC VNX – How to create a Storage Group

As my 2015 resolution I decided to write a little bit more with practice examples of some day-to-day tasks that you can come across when working with Storage Arrays. Lately I have posted a quick introduction to EMC VNX, if you haven’t read it yet, give it a try: EMC VNX – Unisphere – Quick overview.  Today I would like go to thru the process of creating a Storage Group, masking a LUN and connecting a host. Those are basics steps to actually privision the storage from EMC VNX. So, let’s start

Create a LUN

First step is to create a LUN. I will use graphic interface in this example to guide you thru the process. So, first you have to log in to EMC Unisphere and choose the VNX array you wish to work with. Once it’s done, go to the top menu and select a Storage section, choose LUN

Unisphere Storage menu

Unisphere Storage menu

Once you choose the option you should see list of all your LUNs already created and at the bottom of the screen you will find ‘Create’ button

Unisphere - LUN section

Unisphere – LUN section

You can personalize the view of the table or export it for example to CSV and more. But here we focus on adding new LUN. When you click Create button you will see new pop-up window like that:

Create new LUN

Create new LUN

Of course your view won’t be identical. It all depends on your configuration. In that example there is a pool created from RAID6 groups called ‘Pool-Bronze’.

The basic things you should fill and understand is :

  • Do you want Pool LUN or RAID Group LUN?
  • Should the LUN be thin provisioned, should it be deduplicated?
  • what should be the capacity, and what should be the LUN ID

In our example we are going to create a Pool LUN, with size of 100 GB. For that I will use already defined and already created Storage Pool called  Pool-Silver. I will make the pool Thin (which in few words means that the LUN will not take 100GB of my available capacity but more or less the size that is actually used by a host, so at the beginning it will be very small). I will choose the LUN ID to 43023 (just an example, not any particular reason for that – but you have to remember that LUN ID is unique for a storage system. And I will call the lun testlun_1. Again the LUN Name is unique as well.

Create new LUN

Create new LUN

After you click ‘Apply’ you will be promped for confirmation, and once given, the LUN should be created in couple of seconds, with information ‘success’.

That’s it. LUN created, piece of cake, right?

Connect a Host

In first step we have created a LUN. Now we need a host that can access the LUN. In my example we will create a new host. Let’s assume an example: there is a new host being installed in our environment. It’s not powered up yet but we know it’s HBA WWN (WWpN /WWnN).

Since it’s not powered up yet, we will not see it in our hosts available. In real life situation the host would be probably first connected and either auto-registered with Host Agent or Unisphere Server Utility (or similar software), or we would have to manually register the host.

In our example we will go straight to manual registration.

For that go to Host section in menu and choose Initiators.


Unisphere Host menu

Unisphere Host menu

All hosts connected to SAN have Initiators (at least one). Initiator is a pair of  WWN/IQN address and Storage Processor Port that it’s connected to.

You should see a table similar to this one:

Unisphere - Initiators

Unisphere – Initiators


OK – this is getting tricky how to not make this post confusing and too complicated. What you see is list of Initiators. Very important rule: One initiator might be only in one Storage Group. Period. No exception. The rule is that one host can be in one Storage Group. But if you look closely at this table you will notice that usually one host have more than one initator, therefore there is a trick to put single host in more than one Storage Group.

Let me first give you an example how usually the connection between Host and Storage Array looks like:

Most often we should have at 4 Initiators per host:

  1. host_HBA_1 connected to Port_X in Storage Processor A
  2. host_HBA_1 connected to Port_Y in Storage Processor B
  3. host_HBA_2 connected to Port_Z in Storage Processor A
  4. host_HBA_2 connected to Port_U in Storage Processor B

In such configuration we should have basically no single point of failure to break the connection between storage and Host. Of course I assume that there are two Fabrics as well.

But let’s not make this post to complicated. We will add a host with Single Initiator connected to Storage Processor A port 5. At the bottom of the screen you should notice an option Register.

Create Initiator Record

Create Initiator Record

As you can see the WWN (WWnN:WWpN)  in example is not a valid address, but it’s good enough for our example. I have selected port A-5, Failover Mode Active-Active (ALUA), and register it as a new Host called test_host with some local IP address.

I don’t want to go in the details right now of all the options. Just click OK.

Create Initiator Record

Create Initiator Record

Success. We have created a new Host. Of course it’s not connected. But assuming that we have put valid WWN once the host is connected to the selected port (in my example SPA-5) it will be up and running.

Unisphere - Initiator

Unisphere – our “fresh” Initiator

There it is – our fresh Host with one initiator. As you can notice it’s a part of ~management Storage Group. That it’s actually a special SG, where all Initiators are put if that are in no “real” Storage Group.

OK… To confirm that our freshly added Host exist let’s go to Host List option (also in Host menu)

Unisphere Host List

Unisphere Host List

As you can notice it’s Manually Registered. Again – task completed. We have our new host added to the Storage System (not physically connected, but that’s OK).

 Create a Storage Group

If you are not sure what Storage Group is and why we actually need it, go thru this post: EMC VNX – Access Logix, LUN masking and Storage Groups.

To Create a Storage Group simply go to Host > Storage Group section. Click Create and all you have to give is a name:

Create Storage Group

Create Storage Group

I have created the Storage Group called new_SG. Once you hit OK you will be prompted with question: are you sure..? Of course I’m sure! Then you should get a window like that:

new Storage Group

new Storage Group

As you can see, the job status is success and we can actually straight away say “Yes, I want to add LUNs and/or connect host”Let’s do it. next sreen you can see is:

Adding LUNs to Storage Group

Adding LUNs to Storage Group

Fist you have a choice to Add LUN(s). I have look for the LUN I have created in step 1, click on it, and click ‘Add’ on the right side.

Now, there is an important thing right here.. Choosing Host LUN ID. As you can see I didn’t put any value, the storage system will auto assign the Host LUN ID with the next available (in this case it will be 0, since there is no LUN present in this Storage Group). To learn more about HLU/ALU again, take a look at post EMC VNX – Access Logix, LUN masking and Storage Groups.

You cat ‘hit’ OK, or Apply. If you plan to attach some hosts as well, just hit Apply, which will add the selected LUN and will not close the window. Look: Connecting Host is just another tab on the same window.

Connect Host to Storage Group

Connect Host to Storage Group

All you have to do is select from hosts available in left field and move it to the right. Note that you can filter for Host Already connected, but if you choose from hosts that are already connected you will remove the host from the current Storage Group and move it to the new one (really, really dangerous idea, if you are not aware of that!). As I mentioned before, there is a way of putting same Host in two different Storage Groups, but let’s keep it for another post.


It may look a little bit complicated at first, and actually you have to be really careful during all operations. But at the end, if you stay focused it’s not that big of a deal. I think the most important things you should remember are:

  • You can add same LUN to few Storage Groups. Just change “Show LUNs” option to see LUNs already connected to different Storage Groups
  • You can add (by default) one host to only one Storage Group! If you choose the host that is a part of different Storage Group you will remove it from the first one. Make sure you know what you are doing! If the Host is part of ~management storage group you are good to go – it’s “special container” for all not-assigned Hosts.

EMC VNX – Unisphere – Quick overview

I already wrote few words about Unisphere in post EMC VNX – How to use Unisphere. In this post I would like to show you a little bit more in practice how you can start working with EMC Unisphere.

How to launch?

As I mentioned in my previous post, easiest way to launch is to fire up and Internet Browser and type the IP address of Control Station. TIP: You have to have Java installed and available.

When you see login screen just login with your credentials. If you log in for the first one you can probably login with the standard credentials:

* login: sysadmin
* password: sysadmin

Worked? Great. After you log in you should see screen like the one below:

Unisphere Dashboard

Unisphere Dashboard

I have added few comments in red. First thing you have to notice is that you see a Dashboard. If you have more then one VNX in the domain you are actually not yet login to the specific VNX, but for the overall dashbord (of course it depends on the Scope of your credentials, but I assume you login as a sysadmin).

If you would like to work / manage single storage system you have to choose it, either from drop-down list in top left corner, or click on the hostname below the menu.

Working with Storage Array

Once you have selected a desired VNX Array your Dashbord should change a little, and look more like:

Unisphere VNX Dashboard

Unisphere VNX Dashboard

It is opened in the same window. You have more specific information about your Array. First you see all important (recent) system alerts. On the right top window you should see basic information, hint: here you will find serial number, often needed 🙂

Let’s take a quick tour thru the menu options


Unisphere System menu

Unisphere System menu

Each menu have several options. You can either click on the top menu choise (System,Storage,Host,Data Protection etc.) or just hover over it and wait to more options to pop up. System have three choices:

  •  Hardware – here you can find all hardware information, from single harddrive information to FAN status.
  •  Monitoring and Alerts – all alerts are here, you can gather SP Event Logs, Notifications, Statistics and more, even schedule sending e-mail with statistics.
  •  Reports – place where you can generate reports


Unisphere Storage menu

Unisphere Storage menu

This tab will be probably often visited in your daily tasks. The number of options available here may vary depends on version, licenses etc. For example if you have VNX for file, you would see here much more :).

In this section you can actually provision Storage, create LUN’s or Storage Pools, etc. More detailed examples I will put in the short future.


Unisphere Host menu

Unisphere Host menu

In this tab the most important section is probably Storage Groups where you can define new, delete old or modify already existing Storage Groups. But of course to create a Storage Group that has any kind of purpose you have to have a Host, list of hosts you can find in Host List. Let’s go a little bit deeper, to have Host you can actually need to have some Initator.In this post I don’t want to go deeper, but I promise I will explain more in future posts.


OK, we have already quite a long article, I hope this give you a basic overview how to even start working with  Unisphere. Have fun and be extra careful, do not experiment with any ‘production’ VNX! 🙂


It might be a little confusing at the beginning to understand the difference between FAST Cache and FAST VP. Both are created from FLASH drives, and both have very similar, performance wise, advantages. But those are different technologies. First of all, FAST Cache you set up on Storage System level, so everything provisioned on the Storage Array can take an advantage, both RAID LUNs and pool LUNs. FAST VP is created in a Storage Pool, and can be used only for LUNs within that Storage Pool.

Take a look at comparison created by EMC to see all the main differences.

Allows Flash drives to be used to extend the existing caching capacity of the whole storage system Allows a single LUN to leverage the advantages of multiple drive types through the use of storage pools.
Granularity is 64 KB Granularity is 1 GB
Data that is accessed frequently is copied from HDDs to Flash drives Data is moved between different storage tiers based on statistics collected over a period of time
Use when workload changes are unpredictable and very dynamic, and require a quick response time Use when workload pattern changes are predictable and relatively low.
Constantly promotes frequently accessed HDD data to FAST Cache. There are no relocation cycles. Data movement occurs in scheduled or manually invoked relocation windows
Calculation to decide which data needs to be promoted to FAST Cache is performed continuously. Calculation to decide which portion of data need to be moved is performed once every hour.

Of course you can use both at the same time: FAST Cache and FAST VP to yield high performance from the storage system. For example, you can use Flash drives to create FAST Cache, and use FAST VP for storage pools consisting of SAS and NL-SAS drives. Or even devide your Flash drives into two groups: one for FAST Cache usage, and second to use it in ‘extreme performance’ tier for your important storage pool.

If you use both FAST VP and FAST Cache, if FAST VP moves a chunk of data to Flash drives, FAST Cache will not promote that chunk of data into FAST Cache.