Dell EMC VxRail Appliance, Руководство по эксплуатации

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27 | Dell EMC VxRail Appliance Operations Guide
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vSAN Storage Policy Based Management
vSAN Storage Policy Based Management (SPBM) streamlines storage provisioning and
simplifies storage management. A default storage policy is assigned when a VM is created. The
policy defines how an object is configured on the vSAN datastore and defines performance and
availability.
vSAN monitors and reports on compliancy with the policy. If requirements change, you can
modify the assigned policy or assign a different policy. You can do this can online without
impacting availability.
The figure below shows the relationship between SPBM policy and a virtual machine, and how
the policy impacts the capacity, availability and performance of a virtual machine.
Figure 13. Storage Policy Based Management
A default storage policy is configured when the system is initialized. You can use the vSphere
web client to configure new policies based on a set of rules. The table below summarizes vSAN
policy rules.
Table 1. vSAN policy rules
vSAN SPBM Rule Description and Recommendation
Failures to tolerate
(FTT) Defines number of host, disk or network failures that a storage object can
tolerate. When Failure Tolerance Method is set to Mirroring to tolerate “n”
failures; “n+1” copies of the object are created and “2n+1” hosts (or fault
domains) are required.
When the Failure Tolerance Method is Erasure Coding and Failure to
Tolerate=1, RAID5 3+1 is used and 4 hosts (or fault domains) are required. If
Failure to Tolerate =2, RAID6 4+2 is used and 6 hosts (or fault domains) are
required. Default value is 1. Maximum value is 3.