Scsp Info; Introduction To Info; Getting Replica Counts; Getting Node Status And Cluster Capacity - Dell DX6000 Application Manual

Chapter 11. SCSP INFO
The following topics in this chapter discuss details about SCSP INFO:
• Section 11.1, "Introduction to INFO"
• Section 11.2, "Unnamed Object INFO Details"
• Section 11.4, "Error Responses to INFO"

11.1. Introduction to INFO

This section discusses general information about SCSP INFO that applies to both named and
unnamed objects.
The INFO message is a request that is identical in semantics to the READ request, except that the
content stream, if found, is not returned in the response. If the referenced content is found in the
cluster, only the meta-information about that stream is returned in the form of response headers.
The INFO request is formatted as a simple HTTP request using the HEAD method as shown in the
following examples:
• Named object
HEAD /mybucket/samplefile.txt HTTP/1.1
Host: cluster.example.com
User-Agent: DX Storage Client/0.1
• Unnamed object
HEAD /06eec5e2c3f1aadcb41ef7fd52adc049 HTTP/1.1
Host: cluster.example.com
User-Agent: DX Storage Client/0.1

11.1.1. Getting Replica Counts

The query argument countreps=yes can be used to request that INFO return the number of
replicas of a stream that are online in the cluster. This was previously the default behavior but
was changed in the 4.0 release so that replicas are not counted unless specifically requested.
Therefore, if you wish DX Storage to return the replica count of a stream, you should include the
query argument as follows.
HEAD /mybucket/samplefile.txt?countreps=yes HTTP/1.1
Host: cluster.example.com
User-Agent: DX Storage Client/0.1

11.1.2. Getting Node Status and Cluster Capacity

An INFO request submitted without a name or UUID returns counts for high-level node operations
(read, write, delete, and so on), as well as cluster-wide Space Available and Total Capacity values.
This information is also available in the Admin Console.
HEAD / HTTP/1.1
Host: cluster.example.com
User-Agent: DX Storage Client/0.1
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December 2010