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- Hello everybody, my name is Raman Kumar.
I'm a Principal Program Manager
in the Azure Disk Storage Team.
And today we are going to talk about
our new offering called
Zone Redundant option for Azure Disk Storage.
So before we talk about ZRS option,
let's talk about Azure Disk Storage.
Azure Disk Storage is the storage
that you attach to a IaaS virtual machine in Azure.
We provide various options
for various workload that you may need.
And as you can see in the slide,
we have, currently four options.
And as you go from left to right,
the performance of these different types increase.
And then the latency reduces.
For example, Ultra Disk provides
sub-millisecond latency
for very performance sensitive workload,
such as SAP HANA.
And then, if you look at our standard SSD offering,
it is recommended for dev test workload
wherein you don't need a lot of performance.
And as you go from left to right,
the price also increases.
Now with that, let's talk about our new offering.
And to understand the benefit of ZRS option,
let's compare the ZRS option with our current offering,
which is called Locally Redundant Storage Disks,
or LRS disks.
So when you write data to LRS disk,
the system replicates that data
three times in the same datacenter.
So, LRS disk protects you from node failures,
it protects you from rack failures
that can happen in that datacenter.
Whereas, in case of ZRS Disk,
when you write any data,
the system replicates that data to three different zones.
So that these ZRS disks can be available,
even when an entire zone is down due to natural disaster,
or due to hardware failures.
ZRS disk is available, currently,
only for two disk types,
which are standard SSD and premium SSD.
And they are priced 1.5 X the LRS option.
And we recommend you to use it for various scenarios.
Such as, you can use it as a shared disk
for your clustered application.
You can use it for legacy application
that cannot replicate data itself to a different zone
to get higher availability.
Or, you can use it in combination with
your multi-zone, Azure Kubernetes clusters.
We are going to look at each of these options.
So, let's start looking at first, a clustered application.
So as you can see in this diagram,
ZRS disk is used as a shared disk
which is attached to two different VMs,
in two different zones.
And currently, VM one is the active VM.
So it means that all the traffic
is coming to the VM in Zone one.
Now let's take a scenario when Zone one goes down.
And then, what will happen, that Windows Server
will detect that now VM one is down,
and then it will automatically failover
the cluster to the VM in secondary zone.
And then, it is able to do it with all the data intact
because the shared ZRS disk
will continue to be available, even when Zone one is down.
So that's the benefit of using ZRS disk.
It will increase the availability of your clusters,
which requires shared storage.
Now, let's look at this in action.
Let's first look at our shared ZRS disk
that I have already created.
And you can see here, the disk sku for this disk
is Premium SSD ZRS.
And then, here you can see
that the maximum shares that this disk support is three,
which means that it's a shared disk.
Basically, you can attach this disk
to three VMs at the same time.
And currently this disk is not attached to any VM.
So now what we are going to do is attach this disk
to two different VMs, in two different zones,
and see if it works.
So, I have already created two VMs,
so let's pick one of these VMs.
And then you can see, here,
that this VM is created in Zone one.
And we'll go ahead and try to attach
the shared ZRS disk to this VM.
So, let's find that shared ZRS disk
that I have already created.
So this is the one.
And then, once you click on Save,
in a few seconds, this disk will be attached
to the VM in Zone one.
Now, while this is being done,
let's go and try to attach the disk to the second VM.
Oh, it happened.
So you don't have to wait for it.
So it's all done, it's so quick.
So now, let's go and find the second VM,
which is created in the second zone.
So you can see, here, that this VM
is created in Zone two.
And then, we'll follow the same process.
We'll go to the disks blade,
and then click on "attach existing disks" button,
and then we'll find our disk, the shared ZRS disk,
and then attach it to the second VM.
And in a few seconds, you will see that this disk
is now shared with two different VMs
in two different zones.
And now you're ready to configure failover applications,
such as Windows Server failover cluster.
Now let's look at other use cases of using ZRS disk.
In this example, we'll look at how ZRS disk
complements a multi-zone AKS cluster.
In multi-zone AKS clusters,
you can spread the VMs in different zones
so that your application is not impacted
when VMs in one zone goes down.
Now, let's say you want to host
a stateful application on top of
this multi-zone AKS cluster.
Now, for that, you need to store the data
on a storage that can survive
even when an entire zone goes down.
So, let's take an example that Zone one
is down due to a natural disaster,
or due to hardware failures.
Now AKS will detect that, and it will move the pod
that was hosted in Zone one
by moving the pod to a VM in a different zone.
And then, it will attach the ZRS disk
to the node in Zone two, for example.
And in this case,
the application won't be impacted.
The application hosted on the multi-zone AKS cluster
will continue to run, providing you higher availability.
Now, let's look at another use case,
which typically
will be useful for a legacy application.
When I say legacy application,
I mean that an application
that is not advanced enough
to replicate the data to a different zone.
Many modern applications like SQL AlwaysOn or Cassandra,
can replicate data to a different zone
providing higher availability.
But legacy applications are typically not designed
to handle such a scenario.
In those cases, you can take advantage of ZRS disk.
So let's take an example,
that you're using a single VM
with all the disks using ZRS storage.
Now, let's say, currently the VM is hosted in Zone one,
and then Zone one goes down.
Now what you can do, is that you can force delete
the VM in Zone one, which will automatically detach
the ZRS disk from the VM in Zone one.
And now you can attach the ZRS disk
by creating another VM in a different zone,
and then bringing up your application within seconds,
getting higher availability for your application.
So that is another very important benefit of ZRS disk.
An important scenario that you will be able to handle.
Now currently, forced delete operation,
it is currently in preview.
Very soon we will take it to general availability,
and then you'll be able to use it for this scenario.
Here are the different links that you can use
to learn more about ZRS disk, and also shared disks.
And then, you can also find a link to request new regions
where, currently ZRS disk is not available,
if you need it for your scenario and workload.
And then, you can know more about Azure Disk Storage,
as well, there's a link.
And then finally, if you have any questions and concerns,
you can always reach out to us
at AzureDisks@microsoft.com.
Thanks a lot.
I hope this session was very useful
and looking forward to all the feedback.
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