Spectra Logic

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Create Azure Target Read Preference

Description

Create an Azure target read preference for a particular bucket, overriding the default defined in the Azure target configuration.

Requests

Syntax

POST http[s]://{datapathDNSname}/_rest_/azure_target_read_preference​?bucket_id={string}&read_preference=LAST_RESORT|AFTER_ONLINE_POOL|​​AFTER_NEARLINE_POOL|​​AFTER_NON_EJECTABLE_TAPE|​​MINIMUM_LATENCY|​​NEVER&target_id={string}

Request Parameters 

Parameter	Description	Required
bucket_id	Bucket UUID, name, or other unique attribute.	yes
read_preference	When it is preferable to read from the Azure target rather than the replication source. Values: § LAST_RESORT — The target is only used to service a read request if it cannot be serviced locally. This setting should be used in most circumstances. § AFTER_ONLINE_POOL — If data is not available locally on cache or online pool, the target is used to read the data if possible. § AFTER_NEARLINE_POOL — If data is not available locally on cache, online pool, or nearline pool, the target is used to read the data if possible. § AFTER_NON_EJECTABLE_TAPE — If data is not available locally on cache, online pool, nearline pool, or non-ejectable tape, the target is used to read the data if possible. § MINIMUM_LATENCY — The source BlackPearl system reads the data from the data partition with the least latency no matter whether it is connected to the source system or the target. Use this when 1. the cost of the network link to the target is very inexpensive, 2. minimizing latency of servicing GET and VERIFY jobs is critical, and 3. the network throughput to the target is much higher than the tape backend throughput (for example, if the network link to the target is 1 Gb/s, but the tape backend consists of 8 LTO-7 drives, it is very possible that it is faster to service requests locally, even though we must go to tape, since the pipe to the tape backend far exceeds that to the target). § NEVER — The target is never allowed to service a read request. You may want to use this setting when the cost of the network link to the target is very high, or if for data integrity verification purposes, the administrator wants to ensure that all GET and VERIFY requests are serviced locally.	yes
target_id	BlackPearl target UUID, name, or other unique attribute.	yes

Responses

Response Elements

<Data>
   <BucketId>{string}</BucketId>
   <Id>{string}</Id>
   <ReadPreference>
      MINIMUM_LATENCY|AFTER_ONLINE_POOL|AFTER_NEARLINE_POOL
      |AFTER_NON_EJECTABLE_TAPE|LAST_RESORT|NEVER
   </ReadPreference>
   <TargetId>{string}</TargetId>
</Data>

where the response elements are defined as follows:

Parameter	Description
BucketId	The container for the response.
Id	The UUID for the read preference.
ReadPreference	When it is preferable to read from the Azure target rather than the replication source. Values: MINIMUM_LATENCY, AFTER_ONLINE_POOL, AFTER_NEARLINE_POOL, AFTER_NON_EJECTABLE_TAPE, LAST_RESORT, NEVER. See read_preference.
TargetId	The UUID for the replication target.

Example

Sample Request

This request overrides the read preference for the Azure target with the UUID 26bbc55a-417a-49a9-90f5-dbc3920cb0fc to set the read preference for ‘bucket1’ to MINIMUM_LATENCY.

POST http[s]://blackpearl-hostname/_rest_/azure_target_read_preference?bucket_id=bucket1​&read_preference=MINIMUM_LATENCY&target_id=26bbc55a-417a-49a9-90f5-dbc3920cb0fc HTTP/1.1

Sample Response

HTTP/1.1 201 CREATED
<Data>
   <BucketId>502e2d43-fe83-491e-985c-5f4d8d2108c3</BucketId>
   <Id>4b90e88b-63ec-4784-96a3-8408e74ad3ec</Id>
   <ReadPreference>MINIMUM_LATENCY</ReadPreference>
   <TargetId>26bbc55a-417a-49a9-90f5-dbc3920cb0fc</TargetId>
</Data>