Dell EMC VxFlex Ready Node, User Manual

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Thick
Capacity is allocated immediately, even if not actually used. This can cause
capacity to be allocated, but never used, leading to wasted capacity.
Thick capacity provisioning is limited to available capacity.
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Thin
Capacity is “on reserve,” but not allocated until actually used. This policy
enables more flexibility in provisioning.
Whereas thick capacity is limited to available capacity, thin capacity
provisioning can be oversubscribed, as follows:
Maximum thin capacity provisioning = 5 * (gross capacity - used capacity)
When capacity usage reaches the level where it may cause IO errors, alerts are
generated. At certain higher capacity levels, volumes (even thin volumes) can
no longer be created.
Example:
In a system with 3 SDSs, each with 10 TB, there are 30 TB of storage.
In the system, there is already a thick-provisioned volume that takes up 15 TB
of the gross capacity (created by adding a 7.5 TB volume).
MDM will allow a total of 300 TB gross to be provisioned, and since 15 TB are
already allocated, you can add a thin-provisioned volume of 285 TB gross (by
adding a 142.5 TB volume) or a thick-provisioned volume of 15 TB gross.
2. Map volumes. Designate which SDCs can access the given volumes. This gives rise
to the following:
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Access control per volume exposed
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Shared nothing or shared everything volumes
Once an SDC is mapped to a volume, it immediately gets access to the volume
and exposes it locally to the applications as a standard block device. These
block devices appear as
/dev/scini X
where X is a letter, starting from “a.”
For example:
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/dev/scinia
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/dev/scinib
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The maximum amount of partitions for the scini disk is 15.
3. The maximum amount of volumes that can be mapped to an SDC is listed in the
“Product capabilities and system” table.
Note: SDC mapping is similar to LUN mapping, in the sense that it only allows
volume access to clients that were explicitly mapped to the volume.
This is the end of the system setup.
Implementing VxFlex OS over a virtual system
This section provides an overview of how VxFlex OS is implemented in a virtualized
environment.
VxFlex OS implementation in an ESXi-based system
In the VMware environment, the MDM and SDS components are installed on a
dedicated SVM, whereas the SDC is installed directly on the ESXi host.
Implementation
Architecture
70 Dell EMC VxFlex Ready Node AMS User Guide