Cisco Cisco HyperFlex HX220c M4 Node White Paper

Page 7 of 31

Storage

Physical storage in Cisco HyperFlex Systems is provided by individual hyperconverged nodes in the cluster. A

converged node provides computing and memory resources, an SSD-based cache layer for staging read and write

operations, and a capacity layer that includes varying numbers of spinning media (HDDs) for persistent storage.

Cisco HyperFlex software consolidates isolated pockets of storage from individual converged nodes into a log-

structured file system called the Cisco HyperFlex HX Data Platform. The log-structured file system assembles

blocks to be written to the cache until a configurable write log is full or until workload conditions dictate that it be

destaged to a spinning disk. When existing data is (logically) overwritten, the log-structured approach appends a

new block and updates the metadata. When the cache is destaged, the write operation consists of a single disk

seek operation with a large amount of data written. This approach improves performance significantly compared to

the traditional read-modify-write model, which is characterized by numerous seek operations and small amounts of

data written at a time.

Data blocks written to disk are compressed into objects and sequentially laid out in fixed-size segments. The

objects are distributed across all nodes in the cluster to make uniform use of storage capacity. By using a

sequential layout, the platform helps increase flash-memory endurance and makes the best use of the read and

write performance characteristics of HDDs, which are well suited for sequential I/O. The platform includes

enterprise features such as thin provisioning, space-efficient clones, and snapshots for data protection. Inline

deduplication and compression are turned on by default and contribute to significant increases in resource

utilization.

Because read, modify, and write operations are not used, compression and snapshot operations have little or no

performance impact. The file system has been designed from the foundation to provide very efficient mechanisms

for deduplication, compression, and snapshotting.

VMware vSphere

VMware vSphere provides a common virtualization layer (the hypervisor) for a computer’s physical resources: the

VMware ESX host. The hypervisor allows provisioning of precisely controlled and fully functional virtual machines

with the required CPU, memory, disk, and network connectivity characteristics. Virtual machines can run the

operating system and application workload of choice in an isolated manner for increased utilization of the

underlying hardware.

The high-availability features of VMware vSphere 6.0 that are relevant to this solution include the following:

●

VMware vMotion: Provides live migration of virtual machines within a virtual infrastructure cluster, with no

virtual machine downtime or service disruption

●

VMware Storage vMotion: Provides live migration of virtual machine disk (vmdk) files between data stores

whether within or across storage arrays, with no virtual machine downtime or service disruption

●

VMware vSphere High Availability: Detects and provides rapid recovery for a failed virtual machine in

a cluster

●

VMware Distributed Resource Scheduler (DRS): Provides load balancing of computing capacity in

a cluster

●

VMware Storage Distributed Resource Scheduler (SDRS): Provides policy-based storage management,

such as load balancing across multiple data stores based on space use and I/O latency