Request Syntax Request Parameters Response Syntax Response Elements Errors Examples See Also

DescribeCache

Returns information about the cache of a gateway. This operation is only supported in the cached volume, tape, and file gateway types.

The response includes disk IDs that are configured as cache, and it includes the amount of cache allocated and used.

Request Syntax


{
   "GatewayARN": "string"
}

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

The request accepts the following data in JSON format.

GatewayARN

The Amazon Resource Name (ARN) of the gateway. Use the ListGateways operation to return a list of gateways for your account and Amazon Web Services Region.

Type: String

Length Constraints: Minimum length of 50. Maximum length of 500.

Required: Yes

Response Syntax


{
   "CacheAllocatedInBytes": number,
   "CacheDirtyPercentage": number,
   "CacheHitPercentage": number,
   "CacheMissPercentage": number,
   "CacheUsedPercentage": number,
   "DiskIds": [ "string" ],
   "GatewayARN": "string"
}

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

CacheAllocatedInBytes

The amount of cache in bytes allocated to a gateway.

Type: Long

CacheDirtyPercentage

The file share's contribution to the overall percentage of the gateway's cache that has not been persisted to Amazon. The sample is taken at the end of the reporting period.

Type: Double

CacheHitPercentage

Percent of application read operations from the file shares that are served from cache. The sample is taken at the end of the reporting period.

Type: Double

CacheMissPercentage

Percent of application read operations from the file shares that are not served from cache. The sample is taken at the end of the reporting period.

Type: Double

CacheUsedPercentage

Percent use of the gateway's cache storage. This metric applies only to the gateway-cached volume setup. The sample is taken at the end of the reporting period.

Type: Double

DiskIds

An array of strings that identify disks that are to be configured as working storage. Each string has a minimum length of 1 and maximum length of 300. You can get the disk IDs from the ListLocalDisks API.

Type: Array of strings

Length Constraints: Minimum length of 1. Maximum length of 300.

GatewayARN

The Amazon Resource Name (ARN) of the gateway. Use the ListGateways operation to return a list of gateways for your account and Amazon Web Services Region.

Type: String

Length Constraints: Minimum length of 50. Maximum length of 500.

Errors

For information about the errors that are common to all actions, see Common Errors.

InternalServerError

An internal server error has occurred during the request. For more information, see the error and message fields.

HTTP Status Code: 400

InvalidGatewayRequestException

An exception occurred because an invalid gateway request was issued to the service. For more information, see the error and message fields.

HTTP Status Code: 400

Examples

Return information about a gateway's cache

The following example shows a request to obtain a description of a gateway's working storage.

Sample Request


POST / HTTP/1.1
Host: storagegateway.us-east-2.amazonaws.com
Content-Type: application/x-amz-json-1.1
Authorization: AWS4-HMAC-SHA256 Credential=AKIAIOSFODNN7EXAMPLE/20120425/us-east-2/storagegateway/aws4_request, SignedHeaders=content-type;host;x-amz-date;x-amz-target, Signature=9cd5a3584d1d67d57e61f120f35102d6b3649066abdd4bf4bbcf05bd9f2f8fe2
x-amz-date: 20120912T120000Z
x-amz-target: StorageGateway_20120630.DescribeCache

{
    "GatewayARN": "arn:aws:storagegateway:us-east-2:111122223333:gateway/sgw-12A3456B"
}

Sample Response


HTTP/1.1 200 OK
x-amzn-RequestId: gur28r2rqlgb8vvs0mq17hlgij1q8glle1qeu3kpgg6f0kstauu0
Date: Wed, 12 Sep 2012 12:00:02 GMT
Content-Type: application/x-amz-json-1.1
Content-length: 271

{
    "CacheAllocationInBytes": "2199023255552",
    "CacheDirtyPercentage": "0.07",
    "CacheHitPercentage": "99.68",
    "CacheMissPercentage": "0.32",
    "CacheUsedPercentage": "0.07",
    "DiskIds": [
        "pci-0000:03:00.0-scsi-0:0:0:0",
        "pci-0000:04:00.0-scsi-0:1:0:0"
    ],
    "GatewayARN": "arn:aws:storagegateway:us-east-2:111122223333:gateway/sgw-12A3456B"
}