Tag Archives: HyperConverged

Informational

VROC vs Traditional RAID Controller: Optimizing Boot Devices in VMware vSAN Ready Nodes

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The world of data storage is constantly evolving, with technology advancements aiming to maximize performance and efficiency in data center operations. One of the recent innovations in storage technology is Intel’s Virtual RAID on CPU (VROC), which has gained traction among IT professionals and enthusiasts. This article will compare the use of VROC as a boot device to the more traditional RAID controller in a VMware vSAN Ready Node, highlighting the advantages and disadvantages of each approach.

VROC: The New Kid on the Block

Intel VROC is a hybrid software/hardware-based RAID solution that utilizes the CPU for RAID processing rather than a dedicated hardware RAID controller. VROC can be configured using NVMe SSDs (as well as SATA SSDs), offering high-performance storage with lower latency compared to traditional RAID controllers. Let’s dive into some of the advantages and disadvantages of using VROC as a boot device in a vSAN Ready Node.

Advantages of VROC

Performance: VROC allows for better performance and reduced latency by eliminating the need for a dedicated RAID controller. This results in faster data processing and retrieval, which is crucial in virtualized environments.

Scalability: With VROC, you can easily expand your storage capacity by adding NVMe SSDs without the need for additional RAID controllers. This enables seamless growth of your vSAN Ready Node as your storage needs increase.

Cost Savings: VROC can reduce the cost of your vSAN Ready Node by eliminating the need for additional RAID controllers. Furthermore, as a software-based solution, VROC can leverage existing hardware resources, resulting in lower capital expenditures.

Traditional RAID Controller: Tried and Tested

A traditional RAID controller is a dedicated hardware component responsible for managing storage arrays and ensuring data redundancy. These controllers have been widely used in data centers for decades, providing a reliable and stable solution for storage management. Here are some advantages and disadvantages of using traditional RAID controllers as boot devices in vSAN Ready Nodes.

Advantages of Traditional RAID Controllers

Familiarity: Traditional RAID controllers are well-known and widely understood by IT administrators, making them a comfortable and familiar choice for managing storage in vSAN Ready Nodes.

Hardware Independence: Unlike VROC, traditional RAID controllers do not tie you to specific hardware vendors, allowing for more flexibility in hardware selection.

Conclusion

Choosing between VROC and traditional RAID controllers for boot devices in vSAN Ready Nodes ultimately depends on your organization’s priorities and requirements. VROC offers better performance, scalability, and cost savings but comes with vendor lock-in and increased complexity. On the other hand, traditional RAID controllers provide familiarity and hardware independence but may fall short in terms of performance and cost-efficiency.

It is essential to carefully evaluate the specific needs of your environment before deciding which solution is best suited for your vSAN Ready Node. By considering factors such as performance, scalability, cost, and ease of management, you can make an informed decision that will optimize your VMware vSAN Ready Node for long-term success. As storage technologies continue to evolve, staying abreast of new developments, such as VROC, can help ensure your organization remains agile and well-prepared to adapt to the ever-changing data center landscape. Ultimately, the choice between VROC and traditional RAID controllers should be guided by a thorough understanding of your specific storage needs, allowing you to maximize performance and efficiency in your virtualized environment.

Informational

vSAN 7.0U1 – A New Way to Add Capacity

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As we all know there are a number of ways of scaling capacity in a vSAN environment, you can add disks to existing hosts and scale the storage independently of compute, or you can add nodes to the cluster and scale both the storage and compute together, but what if you are in a situation where you do not have any free disk slots available, and / or you are unable to add more nodes to the existing cluster? Well vSAN 7.0U1 comes with a new feature called vSAN HCI Mesh, so what does this mean and how does it work?

Let’s take the scenario below, we have two vSAN clusters in the same vCenter, Cluster A is nearing capacity from a storage perspective, but the compute is relatively under utilised, there are no available disk slots to expand out the storage. Cluster B on the other hand has a lot of free storage capacity but is more utilised on the compute side of things:

Now the vSAN HCI Mesh will allow you to consume storage on a remote vSAN cluster providing it exists within the same vCenter inventory, there are no special hardware / software requirements (apart from 7.0U1) and the traffic will leverage the existing vSAN network traffic configuration.

This cool feature adds an elastic capability to vSAN Clusters, especially if you need to have some additional temporary capacity for application refactoring or service upgrade where you want to deploy the new services but keep the old one operational until the transition is made.

VMware has not left the monitoring capabilities of such use out either, in the UI you can monitor the usage of “Remote VM” from a capacity perspective as well as within the performance service

So this clearly allows dissagregation of storage and compute in a vSAN environment and offers that flexibility and elasticity of storage consumption are there any limitations?

  • A vSAN cluster can only mount up to 5 remote vSAN Datastores
  • The vSAN Cluster must be able to access the other vSAN cluster(s) via the vSAN Network
  • vSphere and vCenter must be running 7.0U1 or later
  • Enterprise and Enterprise Plus editions of vSAN
  • Enough hosts / configuration to support storage policy, for example if your remote cluster has only four hosts, you cannot use a policy which requires RAID6

So this is a pretty cool feature and sort of elliminates the need for Storage Only vSAN nodes which was discussed in the past at many VMworlds

Day-2 Oerations

Day-2 Operations – Performance Monitoring in the vSAN UI

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Performance reporting or Performance Monitoring is something of a must in any storage environment today, I remember many times when I was in VMware Support when facing a customer storage performance issue that metrics were not there to capture the event, and most storage performance tools required enabling, obviously this meant that the issue had to be occurring at the time of the performance metrics grab, vSAN in the early days was no different, vSAN Observer whilst being a detailed tool and provided a lot of information, was not a historical tool, it was enabled to troubleshoot a performance issue that was happening at that particular time.

In the later releases of vSAN the UI came equipped with more performance metrics than you could shake a stick at, which from a performance troubleshooting and monitoring perspective is the dogs danglies, but what does this mean from an every day perspective?  Before we take a look at the UI, there are three areas where vSAN Performance metrics can be displayed

  • Cluster level – This is the performance metrics aggregated for the whole cluster and allow you to have the high level view of how your cluster is performing as a whole
  • Host Level – This allows you to look at how vSAN is performing on a host by host perspective and contains further information drilling down through things like Disk Groups, Physical Disks, Network Controllers, VMkernel interfaces.
  • VM Level – This focuses on a specific virtual machine and the objects associated with it.

So what information do we have exactly for a given observation level?  Well let’s first of all take a look at the cluster level performance information, there are three options under the performance tab for vSAN

  • vSAN – Virtual Machine Consumption
  • vSAN – Backend
  • vSAN – iSCSI

I have met many customers that immediately notice there is a big difference between the Virtual Machine Consumption and the Backend graphs, so before we go any further let’s talk about what each of these specific areas mean.

Virtual Machine Consumption
These graphs represent the values that objects residing on the vSAN Datastore are seeing, now remember everything that exists on vSAN is an object, so consumers that are counted in these graphs are Virtual Machines, Stats Objects etc

Backend
These graphs represent the backend disks associated with vSAN, cache and capacity

Both sets of graphs cover the statistics for:

  • IOPS
  • Throughput
  • Latency
  • Congestion
  • Outstanding I/O

iSCSI
The iSCSI Performance graphs contain all the graphs above with the exception of Congestion, these graphs are in relation to each iSCSI Target/LUN created and each one is selected in turn to review the performance graphs associated.

If we move our focus to a host level, in here we have a number of options in addition to the three we also see at a cluster level, however there is some additional metrics we get at a host level for Virtual Machine Consumption and Backend, in the Virtual Machine Consumption graph we have Local Client Cache Hit IOPS and Local Client Cache Hit Rate

And under Backend we also have some additional graphs for Resync IOPS, Resync Throughput and Resync LatencyThe resync metrics are extremely important if vSAN is recovering from a failure of some sort and performing a resync of degraded components, it is also important if you are performing a pro-active rebalance, policy change or a full data migration during host or disk/diskgroup evacuation.

The other options listed under host vSAN performance are:

  • Disk Group – Shows the performance graphs for the disk groups, I will cover this below as this is one of the most interesting set of metrics with a lot of detail.
  • Disk – Shows the physical disks in the host reporting on IOPS, Throughput and  Latency
  • Physical Adapters – Shows the network stats for each vmnic associated with vSAN, stats include Packet Loss Rate which is good for troubleshooting networking issues
  • VMkernel Adapters – Shows the statistics for each VMkernel configured for vSAN, this also includes a Packet Loss Rate which you can then use to troubleshoot the software network stack
  • VMkernel Adapters Aggregation – This is an aggregation of all VMkernel interfaces being used for vSAN on the host

Now let’s go back to the Disk Group performance graphs, as I said earlier this is a very interesting group of metrics to explore, so what do we have in this group?  The first section is all about Frontend (Guest) IOPS, Throughput and Latency

The frontend statistics are maybe as you have guessed already, they are related to vSAN Object I/O being generated from guests running within the vSAN cluster.  If we scroll down a little further we can see statistics relating to Overhead IO,  Read Cache Hit Rate (for hybrid) and Evictions:

Further down we have statistics relating to the vSAN Write Buffer and De-stage rate clearly showing how much of the write buffer is free and also how quickly data is being de-staged from cache to capacity, now we also have resync metrics under disk groups, however this differs slightly against the Cluster Wide Backend statistics, in the disk group graphs we actually have values that represent various aspects of the Resync Operations, the graph differentiates between:

  • Policy Changes
  • Repairs
  • Rebalance

So you can easily distinguish what resync operations are happening by the statistics within the disk group stats.

Collection Interval
The vSAN Performance metrics collect the sample every five minutes, and this is an average over that five minute period, if your cluster is hardly doing anything (like my cluster for the screenshots) then this can throw out some of the latency numbers, in my own cluster I have noticed it shows higher latency when doing practically nothing than it does when I start putting load on the cluster.  I have spoken to many customers about this, it is no concern, it just means that during the collection sample maybe a few “Large” IO operations returned a larger Latency and because of the low number of samples, this skews the average, so no cause for alarm on that one.

Up next will be Day-2 Operations, Performance Monitoring with vROPS, I just have to write it first 🙂