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  • prefix: ms:
  • schema: b:

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Schema element "b:store"

The store describes how the b:storage will be used.

Definitions

<element name="store" type="b:Store" />

<complexType name="Store">
  <complexContent>
    <extension base="b:Reusable">
      <sequence>
        <element ref="b:shard" [0..∞] />
        <element name="storage" type="b:UnitRef" [0..1] />
      </sequence>
    </extension>
  </complexContent>
</complexType>

Description

One b:namespace can list multiple storage schemes: different approaches to maintain the Unit data. Each store element describes one approach. The store explains when to use which storage back-end will be applied. Those back-ends are Units with role ms:Role/Storage.

The back-end descriptions are owned by the server, and are often not publicly readible. The Namespace (which is readible by the client) only contains the information to knock on the right server door.

element shard

One Namespace can carry many storage references, which may be selected with the when or unless attributes. This way, you MAY, for instance, cause large Units to be stored on other physical places than smaller Units. Or, you can differentiate between types of Units, the first letter of the UnitID, the upload date.

element storage

When there is only one storage back-end, then you can use the simple storage element. But when the configuration gets more complex, you need multiple shards. In that case, the reference of storage will be used when no shard fits.

The following two are the same:

<b:namespace>
  <b:store b:name="default-store" b:when="unit.name like '*.jpg'">
    <b:storage>daemon:Storage/Disk1</b:storage>
  </b:store>
</b:namespace>

<b:namespace>
  <b:store b:name="default-store">
    <b:shard b:when="unit.name like '*.jpg'">
      <storage>daemon:Storage/Disk1</b:storage>
    </b:shard>
    <b:storage>daemon:Storage/Disk2</b:storage>
  </b:store>
</b:namespace>
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