A Diablo Technologies Whitepaper Diablo and VMware TM powering SQL Server TM in Virtual SAN TM May 2015 Ricky Trigalo, Director for Virtualization Solutions Architecture, Diablo Technologies Daniel Beveridge, Senior End-user Computing Architect, Office of CTO, VMware diablo-technologies.com twitter: @diablo_tech Page 1 of 6
Introduction The industry is moving toward converged cloud infrastructure and IT administrators find more workloads being migrated to virtualized environments. VMware is leading the charge with its Software Defined Data Center platform that combines advanced networking and policy based storage, co-located with VM workloads hosted on its industry leading vsphere platform. But hosting large databases in a virtualized environment poses special challenges and IT has often been reluctant to move databases due to the challenges associated with database migration and the performance degradation that may result. VMware Virtual SAN 1.0 made it possible to deploy virtual databases while delivering suitable performance. Now, with Virtual SAN 6.0 optimized for low latency all-flash configurations, deploying a virtualized database has become simpler than ever while offering significant performance gains over previous virtualized database options. This paper will describe a new architecture for high performance databases, with VMware Virtual SAN 6.0 and Diablo Memory Channel Storage (MCS ) at its core. Distribute your Database Tables The current recommended deployment model for running SQL databases in a virtualized environment is to distribute the database tables across multiple Virtual Machines whenever possible (as illustrated in Figure 1). This method leads to increased Transactions per Second (TPS) by maximizing the table distribution. Unfortunately, this deployment method often inhibits the migration of existing databases due to legacy application constraints. When distributing across multiple Virtual Machines is impossible, users are forced to assess alternative deployment methods. With the arrival of Virtual SAN 1.0, VMware broke new ground by combining virtual machine storage with the hypervisor cluster in such a way that each virtual disk could be managed with its own storage policies. The All- Flash capabilities of Virtual SAN 6.0 enables powerful new capabilities that allow for reads to flow directly from the data tier, using the cache tier only for write buffering. High I/O applications such as intensive database workloads now have an opportunity to be serviced atop VSAN s new all-flash logic. High volume reads directly from multiple devices in parallel allowing much higher and more consistent read IOPS per VM than was previously possible. However, without the correct supporting flash hardware, this opportunity for increased parallelism may be squandered by bottlenecks in traditional PCIe and SAS HBA adapters which fundamentally limit the ability to achieve high IOPS and low latency levels simultaneously.this trade-off leads to higher, less consistent latencies, as well as lower overall performance of the database. diablo-technologies.com twitter: @diablo_tech Page 2 of 6
Along with Diablo Technologies Memory Channel Storage, VSAN now makes it possible to deploy existing large databases in a single Virtual Machine (a Monster VM) without any alterations to the database schema or loss of performance (Figure 2). While MCS offers the lowest latencies in general, it also amplifies the benefits of VSAN 6.0 by providing an architecture where the queuing and throttling of SAS HBA and PCIe devices is eliminated and high performance for the most demanding applications is supported. VSAN 6.0 s new read I/O design for all-flash systems allows fully parallel access to devices in the data tier without VSAN 1.0 s mediation of reads through the cache tier. MCS s parallelism offers a perfect match by allowing high volume reads to be serviced in parallel by multiple MCS devices while holding I/O latency to very low levels inside the VM even under loads approaching 100K IOPS. VSAN 6.0 with Diablo MCS for SQL Databases VMware s VSAN platform allows scale out storage without all the complexity and sizing challenges of traditional array platforms. Diablo s Memory Channel storage places flash on the memory bus, offering unprecedented low-latency, scalability and capacity to blade systems. The new VSAN 6.0 all-flash configuration offers improved parallelism. Memory Channel Storage is in the unique position of offering the high performance and low-latencies needed to perfectly complement VSAN s new capabilities. Server Platforms Diablo s MCS technology is offered by several major server OEM s in many rack mount and blade form factors. One particular blade enables an ESXi host with up to 12 Memory Channel Storage DIMMs per host for 4.8TB of flash while still housing up to an additional 576GB of DRAM. Each chassis can house 14 such systems in 10U which means that a standard rack can host up to 56 blades with a total of 268.8 TB of MCS flash capacity. The new features of VSAN 6.0 allow these 12 MCS devices per blade to be divided into two disk groups 1 per socket, with 1 MCS device for VSAN s cache tier and 5 for the data tier. VSAN 6.0 will allow all five MCS devices to service Read I/O requests in parallel allowing demanding databases to achieve high Transactions Per Second (TPS) and low latency around 1ms simultaneously, while preserving very high rack density. diablo-technologies.com twitter: @diablo_tech Page 3 of 6
The Test Setup The graphs below describe how VSAN 6.0 with an MCS all-flash design performs for a single instance database deployment in comparison to a leading All Flash Storage Array. The test compares a single Virtual Machine running multiple Virtual Disks to simulate the single database instance scenario. Configuration Setup 1 Virtual Machine: Microsoft Windows Server 2012 R2 8 vcpu 32GB RAM 20 * 50GB Virtual Disks SQLIO DB 40GB/VMDK 8KB Block Size 4 Threads/VMDK VSAN + MCS Setup 3 Nodes: Lenovo Flex System x280 X6 2 MCS All Flash Disk Groups/Host VSAN + All-flash Array Setup 3 Nodes: HP ProLiant DL380 Leading all-flash Storage Array The Results When using an all-flash array, we observed controller bottlenecks appearing at around 40,000 IOPS, limiting database performance. With VMware Virtual SAN and Memory Channel Storage, the IOPS and Bandwidth continued to increase as we scaled the IOPs to nearly 100,000 IOPS per VM. Figure 3 illustrates the differences in scaling performance between both solutions as the IO load for the database increases. diablo-technologies.com twitter: @diablo_tech Page 4 of 6
In a similar manner, we see that as we scale the number of transactions, the Storage Array cannot maintain the low latencies required. Alternatively, the distribution and parallelism of the VSAN and MCS architecture maintains much lower latency even at a very high number of IOPS. Figure 4 shows this difference in latencies while handling a high number of Transactions Per Second (TPS). Conclusion The combination of VMware s VSAN 6.0, Diablo s Memory Channel Storage technology and the ultradense Flex blade system work together to introduce unprecedented levels of performance while holding costs below those of traditional dedicated database platforms. These savings are due in part to the cost reduction available by servicing demanding databases side by side with other less demanding workloads all on a common converged infrastructure with the high rack density of the blade system. diablo-technologies.com twitter: @diablo_tech Page 5 of 6
While VSAN facilitates high performance by distribution of different SQL tables within a database across multiple hosts in parallel, Diablo MCS flash technology provides highly parallel I/O within each vsan disk group, keeping latency low under high IOPS loads. Unlike other SSD products, MCS flash s physical location in the memory channels brings the application data closer to the CPU, allowing micro-second latencies at the hardware layer. This database design leverages the key advantages of the blade system and Diablo s MCS flash technology to deliver breakout hardware performance and density while fully leveraging the advanced features of VMware s new Virtual SAN 6.0 technology. Companies can now virtualize large and demanding legacy databases on VMware vsan with unprecedented performance, operational simplicity, and reduced cost. About the Authors Ricky Trigalo is Director for Virtualization Solutions Architecture and Partner Management at Diablo Technologies Daniel Beveridge is Sr. End-user Computing Architect, Office of CTO, VMware Special Thanks Fred Schimscheimer, Staff Engineer Office, of the CTO, VMware Ty Flowers, Sr. Solution Engineer, Diablo Technologies diablo-technologies.com twitter: @diablo_tech Page 6 of 6