Glossary

All-Flash Array – a high-speed storage device consisting of just flash technology; it does not use HDDs to store data

Application consistent – ensures that at a given point in time all updates to stored data have been applied; the alternative is crash consistent which can result in partial updates as some data is still in memory

Applications – typical applications that need to be stored and protected include Microsoft Exchange, SQL and SharePoint, Oracle (Database) and SAP

Asynchronous – a form of replication that results in the secondary copy lagging behind the primary (i.e. by 15 minutes)

Backup – the process of taking a copy of an application and its data, either to disk, tape or cloud storage, so that the complete system or individual files/objects can be restored

Cloud compute – resources that provide the ability to run VMs that are accessible over the Internet (e.g. Amazon Web Services)

Cloud storage – resources that provide the ability to store data that is accessible over the Internet (e.g. Amazon S3)

Cluster – a set of nodes (i.e. servers, hosts or storage controllers) that communicate with each other and work toward a common goal (e.g. a vSphere Cluster)

Disaster Recovery (DR) – the process of protecting an infrastructure with a secondary copy at another site; if the primary goes down the secondary will be able to take-over

Distributed Resource Scheduler (DRS) – vSphere feature that automatically load-balances VMs across a cluster

Flash – high-speed persistent (non-volatile) memory technology used in SSDs

Hard Disk Drive (HDD) – mechanical device that utilises rotating platters for storing data that provides a low capacity cost, but poor performance; it is still the primary storage technology where performance is not important

High Availability (HA) – vSphere feature that automatically re-starts VMs on the remaining hosts in a cluster in the event that a host fails; it does result in a small amount of downtime

Host – physical computer (server with CPUs and RAM) that runs a hypervisor

Hyper-converged Infrastructure (HCI) – combines host resources and storage into a single scale-out building block to simplify deployment and management; the alternative is separate hosts and a storage array

Hypervisor – software that allows many instances of an Operating System (such as Windows or Linux) to run on a single host server to significantly increase resource utilisation

Metro Storage Cluster – synchronously replicated storage that supports a vSphere Stretched cluster

Node – a set of devices (i.e. servers, hosts or storage controllers) that communicate with each other to form a cluster

Recovery Point Objective (RPO) – the amount of data lost after a failure

Recovery Time Objective (RTO) – the amount of time it takes to bring a system back on-line after a failure

Replication – technology to copy data from a primary storage device to a secondary; can be bi-directional

Site Recovery Manager – VMware software to automate the movement of VMs between sites for Disaster Recovery and workload mobility

Software-Defined Storage – technology that provides storage services that can run on a wide-range of hardware, that is typically not purchased from the software vendor, with the ability to change the hardware at any point without needing to purchase any new licenses

Solid State Drive (SSD) – Flash based drive that is significantly faster than HDDs, but more expensive – it has become the primary storage technology where performance matters

Storage array – storage device that can be shared between many host servers using SAN (FC and iSCSI) and NAS (CIFS and NFS) protocols

Synchronous – a form of replication that results in the primary and secondary copies being exactly the same

Virtual Machine (VM) – instance of an operating system that runs on a hypervisor; many 10s of VMs can run on a single host

vMotion – vSphere feature that enables a running VM to be moved from one host to another without any downtime

vSphere – VMware’s market leading hypervisor software

vSphere Stretched Cluster – vSphere cluster that is typically spread over two sites, up to 200 km apart, that enables vMotion and HA between those sites; it is a superior form of Disaster Recovery technology

Mark Burgess has worked in IT since 1984, starting as a programmer on DEC VAX systems, then moving into PC software development using Clipper and FoxPro. From here he moved into network administration using Novell NetWare, which kicked-off his interest in storage. In 1999 he co-founded SNS, a consultancy firm initially focused on Novell technologies, but overtime Virtualisation and Storage. Mark writes a popular blog and is a frequent contributor to Twitter and other popular Virtualisation and Storage blog sites.
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About Mark Burgess

Mark Burgess has worked in IT since 1984, starting as a programmer on DEC VAX systems, then moving into PC software development using Clipper and FoxPro. From here he moved into network administration using Novell NetWare, which kicked-off his interest in storage. In 1999 he co-founded SNS, a consultancy firm initially focused on Novell technologies, but overtime Virtualisation and Storage. Mark writes a popular blog and is a frequent contributor to Twitter and other popular Virtualisation and Storage blog sites.

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