PowerFlex: The advantages of disaggregated infrastructure deployments
Mon, 29 Jun 2020 18:57:26 -0000
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For several years, there has been a big push from quite a number of IT vendors towards delivering solutions based on Hyperconverged Infrastructure or HCI. The general concept of HCI is to take the three primary components of IT, compute, network and storage, and deliver them in a software defined format within a building block, normally an x86 based server. These building blocks are then joined together to create a larger, more resilient environment. The software defined components are typically a hypervisor to provide compute, virtual adapters and switches for networking, along with some software that takes the local disks attached to the server, combines them with the disks directly attached to the other building blocks and presents them as a virtual storage system back to the environment.
The HCI approach is attractive to customers for a variety of reasons:
- Easy upgrades by just adding in another building block
- A single management interface for virtual compute, virtual networking and virtual storage
- Having one team to manage everything as it is all in one place
There are of course scenarios where the HCI model does not fit, the limitations are frequently associated with the software defined storage part of the environment, situations such as the following:
- Extra storage is required but additional compute and the associated licensing is not.
- Paying for database licensing on cores that are being used for virtual storage processes.
- Unused storage capacity within the HCI environment that is inaccessible to servers outside the HCI environment.
- A server requirement for a specific workload that does not match the building blocks deployed.
- When maintenance is required it impacts both compute and storage.
Several HCI vendors have attempted to address these points but often their solutions to the issues involve a compromise.
What if there was a solution that provided software defined storage that was flexible enough to meet these requirements without compromise?
Step forward PowerFlex, a product flexible enough to be deployed as an HCI architecture, a disaggregated architecture (separate compute and storage layers managed within the same fabric), or a mixture of the two.
So how can PowerFlex be this flexible?
It is all about how the product was initially designed and developed, it consists predominantly of three separate software components:
- Storage Data Client (SDC): The software component installed on the operating system that will consume storage. It can be thought of as analogous to a Fibre Channel adapter driver from the days of SAN interconnect storage arrays. It can be installed on a wide selection of operating systems and hypervisors, most Linux distributions, VMware and Windows are supported.
- Storage Data Server (SDS): The component that is installed on the server or virtual server providing local disk capacity, it works with other servers installed with the SDS software to provide a pool of storage from which volumes are allocated. It is generally installed on a Linux platform.
- Metadata Manager (MDM): The software management component, it ensures that SDC and the SDS components are behaving themselves and playing nicely together (parents of more than one child will understand).
Each of these components can be installed across a cluster of servers in a variety of ways in order to create flexible deployment scenarios. The SDC and SDS components communicate with one another over a standard TCP/IP network to form an intelligent fabric, this is all overseen by the MDM, which is not in the data path.
Some pictures will help illustrate this far better than I can with words.
By installing the SDC (the C in a yellow box) and the SDS (the S in a green box) on to the same server, an HCI environment is created.
If the SDC and SDS are installed on dedicated servers, a disaggregated infrastructure is created
And because PowerFlex is entirely flexible (the clue is in the name), HCI and disaggregated architectures can be mixed within the same environment.
What are the advantages of deploying a disaggregated environment?
- MAXIMUM FLEXIBILITY - Compute and storage resources can be scaled independently.
- CLOUD-LIKE ECONOMICS – following on from above – what if an application needs to cope with a sudden doubling of compute resource (for example, to cope with a one-off business event)? With a disaggregated deployment, the extra compute-only resources can be added temporarily into the environment, ride the peak demand, then retire afterwards, reducing expenditure by only using what is needed.
- MAXIMISE STORAGE UTILISATION - Completely heterogeneous environments can share the same storage pool.
- CHOOSE THE CORRECT CPU FOR THE WORKLOAD - Servers with frequency optimised processors can be deployed for database use and not require licenses for cores potentially performing processing related to storage.
- AVOID CREATING MULTIPLE ISLANDS OF SOFTWARE DEFINED STORAGE - A mixture of hypervisors and operating systems can be deployed within the same environment; VMware, Hyper-V and Red Hat Virtualisation, along with operating systems running on bare metal hardware, all accessing the same storage.
- UPDATE STORAGE & COMPUTE INDEPENDENTLY - Maintenance can be performed on storage nodes completely independently of compute nodes and vice versa, thereby simplifying planned downtime. This can dramatically simplify operations, especially on larger clusters and prevents storage and compute operators from accidentally treading on each other’s toes!
Whilst HCI deployments are ideal for environments where compute requirements and storage capacity increases remain in lockstep, there are many use cases where compute and storage needs grow independently, PowerFlex is capable of serving both requirements.
PowerFlex was built to allow this disaggregation of resources from day one, which means that there is no downside to performance or capacity when storage nodes are added to existing clusters, in fact there are only positives, with increased performance, capacity and resilience, setting PowerFlex apart from many other software defined storage products.
Related Blog Posts
Introducing NVMe over TCP (NVMe/TCP) in PowerFlex 4.0
Fri, 12 Aug 2022 14:20:34 -0000
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Anyone who has used or managed PowerFlex knows that an environment is built from three lightweight software components: the MDM, the SDS, and the SDC. To deploy a PowerFlex environment, the typical steps are:
- Deploy an MDM management cluster
- Create a cluster of storage servers by installing and configuring the SDS software component
- Add Protection Domains and Storage Pools
- Install the SDC onto client systems
- Provision volumes and away you go!!*
*No requirement for multipath software, this is all handled by the SDC/SDS
There have been additions to this over the years, such as an SDR component for replication and the configuration of NVDIMM devices to create finegranularity storage pools that provide compression. Also added are PowerFlex rack and appliance environments. This is all automated with PowerFlex Manager. Fundamentally, the process involves the basic steps outlined above.
So, the question is why would we want to change anything from an elegant solution that is so simple?
This is due to where the SDC component ‘lives’ in the operating system or hypervisor hosting the application layer. Referring to the diagram below, it shows that the SDC must be installed in the kernel of the operating system or hypervisor, meaning that the SDC and the kernel must be compatible. Also the SDC component must be installed and maintained, it does not just ‘exist’.
In most cases, this is fine and there are no issues whatsoever. The PowerFlex development team keeps the SDC current with all the major operating system versions and customers are happy to update the SDC within their environment when new versions become available.
There are, however, certain cases where manual deployment and management of the SDC causes significant overhead. There are also some edge use cases where there is no SDC available for specific operating systems. This is why the PowerFlex team has investigated alternatives.
In recent years, the use of Non-Volatile Memory Express (NVMe) has become pervasive within the storage industry. It is seen as the natural replacement to SCSI, due to its simplified command structure and its ability to provide multiple queues to devices, aligning perfectly with modern multi-core processors to provide very high performance.
NVMe appeared initially as a connection directly to disks within a server over a PCIe connection, progressing to being used over a variety of fabric interconnects.
Added to this is the widespread support for NVMe/TCP across numerous operating system and hypervisor vendors. Most include support natively in their kernels.
There have been several announcements by Dell Technologies over the past months highlighting NVMe/TCP as an alternative interconnect to iSCSI across several of the storage platforms within the portfolio. It is therefore a natural progression for PowerFlex to also provide support for NVMe/TCP, particularly because it already uses a TCP-based interconnect.
PowerFlex implements support for NVMe/TCP with the introduction of a new component installed in the storage layer called the SDT.
The SDT is installed at the storage layer. The NVMe initiator in the operating system or hypervisor communicates with the SDT, which then communicates with the SDS. The NVMe initiator is part of the kernel of the operating system or hypervisor.
Of course, because PowerFlex is so ‘flexible,’ both connection methods (SDC and NVMe/TCP) are supported at the same time. The only limitation is that a volume can only be presented using one protocol or the other.
For the initial PowerFlex 4.0 release, the VMware ESXi hypervisor is supported. This support starts with ESXi 7.0 U3f. Support for Linux TCP initiators is currently in “tech preview” as the initiators continue to grow and mature, allowing for all failure cases to be accounted for.
NVMe/TCP is a very powerful solution for the workloads that take advantage of it. If you are interested in discovering more about how PowerFlex can enhance your datacenter, reach out to your Dell representative.
Authors:
Kevin M Jones, PowerFlex Engineering Technologist.
Tony Foster, Senior Principal Technical Marketing Engineer.
Twitter: @wonder_nerd
LinkedIn
New File Services Capabilities of PowerFlex 4.0
Fri, 12 Aug 2022 14:25:22 -0000
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“Just file it,” they say, and your obvious question is “where?” One of the new features introduced in PowerFlex 4.0 is file services. Which means that you can file it in PowerFlex. In this blog we’ll dig into the new file service capabilities offered with 4.0 and how they can benefit your organization.
I know that when I think of file services, I think back to the late 90s and early 2000s when most organizations had a Microsoft Windows NT box or two in the rack that provided a centralized location on the network for file storage. Often it was known as “cheap and deep storage,” because you bought the biggest cheapest drives you could to install in that server with RAID 5 protection. After all, most of the time it was user files that were being worked on and folks already had a copy saved to their desktop. The file share didn’t have to be fast or responsive, and the biggest concern of the day was using up all the space on those massive 146 GB drives!
That was then … today file services do so much more. They need to be responsive, reliable, and agile to handle not only the traditional shared files, but also the other things that are now stored on file shares.
The most common thing people think about is user data from VDI instances. All the files that make up a user’s desktop, from the background image to the documents, to the customization of folders, all these things and more are traditionally stored in a file share when using instant clones.
PowerFlex can also handle powerful, high performance workload scenarios such as image classification and training. This is because of the storage backend. It is possible to rapidly serve files to training nodes and other high performance processing systems. The storage calls can go to the first available storage node, reducing file recall times. This of course extends to other high speed file workloads as well.
Beyond rapid recall times, PowerFlex provides massive performance, with 6-nines of availability1, and native multi-pathing. This is a big deal for modern file workloads. With VDI alone you need all of these things. If your file storage system can’t deliver them, you could be looking at poor user experience or worse: users who can’t work. I know, that’s a scary thought and PowerFlex can help significantly lessen those fears.
In addition to the performance, you can manage the file servers in the same PowerFlex UI as the rest of your PowerFlex environment. This means there is no need to learn a new UI, or bounce all over to set up a CIFS share—it’s all at your fingertips. In the UI it’s as simple as changing the tab to go from block to file on many screens.
The PowerFlex file controllers (physical) host the software for the NAS servers (logical). You start with two file controllers and can grow to 16 file controllers. Having various sizes of file controllers allows you to customize performance to meet your environment’s needs. The NAS Servers are containerized logical segmentations that provide the file services to the clients, and you can have up to 512 in a cluster. They are responsible for namespaces, security policies, and serving file systems to the clients.
Each of the file volumes that are provided by the file services are backed by PowerFlex volumes. This means that you can increase file service performance and capacity by adding PowerFlex nodes to the storage layer just like a traditional block storage instance. This allows you to independently scale performance and capacity, based on your needs.
The following table provides some of the other specs you might be wondering about.
Feature | Max |
FS Capacity | 256 TB |
Max file size | 64 TB |
# of files | 10 billion |
# of ACLs | 4 million |
User File Systems | 4096 |
Snaps per File System | 126 |
CIFS | 160000 |
NFS exports | 80000 |
Beyond the architectural goodness, file storage is something that can be added later to a PowerFlex environment. Thus, you aren’t forced to get something now because you “might” need it later. You can implement it when that project starts or when you’re ready to migrate off that single use file server. You can also grow it as you need, by starting small and growing to a large deployment with hundreds of namespaces and thousands of file systems.
With PowerFlex when someone says “file it,” you’ll know you have the capacity to support that file and many more. PowerFlex file services provide the capability to deliver the power needed for even the most demanding file-based workloads like VDI and AI/ML data classification systems. It’s as easy managing the environment as it is integrated into the UI.
If you are interested in finding out more about PowerFlex file services, contact your Dell representative.
Author: Tony Foster
Twitter: @wonder_nerd
LinkedIn
1 Workload performance claims based on internal Dell testing. (Source: IDC Business Value Snapshot for PowerFlex – 2020.)