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VMware storage features
64 Dell EMC SC Series: Best Practices with VMware vSphere | 2060-M-BP-V
16 VMware storage features
The vSphere platform has several features that correspond with SC Series features. This section details
considerations that should be made about features such as Storage I/O Controls (SIOC), storage distributed
resource scheduler (SDRS), and VAAI.
16.1 Storage I/O Controls (SIOC)
SIOC is a feature that was introduced in ESX/ESXi 4.1 to help VMware administrators regulate storage
performance and provide fairness across hosts sharing a volume. Because SC Series storage uses a shared
pool of disks which can have differing performance characteristics, practice caution when using this feature.
Data Progression migrates portions of volumes into different storage tiers and RAID levels at the block level.
This behavior ultimately affects the latency of the volume and could trigger the resource scheduler at
inappropriate times. It may not make sense to use SIOC unless pinning volumes into specific tiers of disk.
In one example that illustrates this scenario (shown in Figure 35), a datastore contains multiple virtual disks,
and each virtual disk has different portions of blocks inT1 and T3. If VM1 begins to read a large amount of
archived data from vm1.vmdk residing on T3 disks, increasing the latency of the datastore above the
congestion threshold. The scheduler could activate and throttle vm3.vmdk although most of its blocks reside
on a separate tier of disks.
Multiple virtual disks with blocks residing in multiple tiers