Information Technology Reference
In-Depth Information
would be used by vSphere's Flash Read Cache caching functionality. See the section on Flash
Read Cache later in this chapter for more details on using solid-state storage for caching.) VSAN
pools the storage across the compute nodes, allowing you to create a datastore that spans mul-
tiple compute nodes. VSAN employs algorithms to help protect against data loss, such as ensur-
ing that the data exists on multiple participating VSAN nodes at the same time.
More information on VSAN is found in Chapter 6, “Creating and Coni guring Storage
Devices.”
vSphere Replication
vSphere Replication brings data replication, a feature typically found in hardware storage plat-
forms, into vSphere itself. It's been around since vSphere 5.0, when it was only enabled for use in
conjunction with VMware Site Recovery Manager (SRM) 5.0. In vSphere 5.1, vSphere Replication
was decoupled from SRM and enabled for use even without VMware SRM.
vSphere Replication enables customers to replicate VMs from one vSphere environment to
another vSphere environment. Typically, this means from one data center (often referred to as
the primary or production data center) to another data center (typically the secondary, backup,
or disaster recovery [DR] site). Unlike hardware-based solutions, vSphere Replication operates
on a per-VM basis, so it gives customers very granular control over which workloads will be
replicated and which workloads won't be replicated.
You can i nd more information about vSphere Replication in Chapter 7.
Flash Read Cache
Since the release of vSphere 5.0 in 2011, the industry has seen tremendous uptake in the use
of solid-state storage (also referred to as l ash storage) across a wide variety of use cases.
Because solid-state storage can provide massive numbers of I/O operations per second
(IOPS) it can handle the increasing I/O demands of virtual workloads. However, solid-state
storage is typically more expensive on a per-gigabyte basis than traditional, hard-disk-based
storage and therefore is often deployed as a caching mechanism to help speed up frequently
accessed data.
Unfortunately, without support in vSphere for managing solid-state storage as a caching
mechanism, vSphere architects and administrators have had difi culty fully leveraging solid-
state storage in their environments. With the release of vSphere 5.5, VMware addresses that
limitation through a feature called
vSphere Flash Read Cache
.
Flash Read Cache brings full support for using solid-state storage as a caching mechanism
into vSphere. Using Flash Read Cache, administrators can assign solid-state caching space to
VMs much in same manner as VMs are assigned CPU cores, RAM, or network connectivity.
vSphere manages how the solid-state caching capacity is allocated and assigned and how it is
used by the VMs.
Hardware vendors that provide solid-state storage devices have partnered with VMware to
make their products fully support Flash Read Cache.
