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A
Diablo
Technologies
Whitepaper
Diablo and VMwareTM
powering
SQL ServerTM
in Virtual SANTM
May 2015
Ricky Trigalo, Director for Virtualization Solutions Architecture, Diablo Technologies
Daniel Beveridge, Senior End-user Computing Architect, Office of CTO, VMware

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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.
VMwareVirtualSAN1.0madeitpossible todeployvirtualdatabaseswhiledeliveringsuitableperformance.
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.

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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.

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The Test Setup
The graphs below describe how VSAN 6.0 with an MCS all-flash design performs for a single instance data-
base 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
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.
VSAN + All-flash Array Setup
•3 Nodes: HP ProLiant DL380
•Leading all-flash Storage Array

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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 ultra-
dense 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.

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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