Retrieve Cache for Nearline Storage

This page gives an overview of tests that can be performed if the application has to use a cache storage for paralleling access of objects from storage systems which provides more bandwidth using multiple connections in parallel.

DICOM objects stored on nearline storage systems may be retrieved back to online storage using an independent storage system specifically intended to be used as a retrieve cache.

Configuration

Below is the basic configuration of nearline and retrieve cache storage systems that need to be done for each of the tests.

Using Archive UI

• Go to Configuration page, Devices tab and edit dcm4chee-arc device. Edit extension of Device Extension, next Edit extension of Archive Device. Create two new Child Object for Storage Descriptor with values as shown below.

Using LDAP

One may

• create a LDIF file (e.g.):

    dn: dcmStorageID=fs1,dicomDeviceName=dcm4chee-arc,cn=Devices,cn=DICOM Configuration,dc=dcm4che,dc=org
    objectClass: dcmStorage
    dcmStorageID: fs1
    dcmURI: ${jboss.server.data.url}/fs1/
    dcmDigestAlgorithm: MD5
    dcmInstanceAvailability: NEARLINE
    dcmProperty: pathFormat={now,date,yyyy/MM/dd}/{0020000D,hash}/{0020000E,hash}/{00080018,hash}
    dcmProperty: checkMountFile=NO_MOUNT
    dcmRetrieveCacheMaxParallel: 10
    dcmRetrieveCacheStorageID: retrieve-cache
    
    dn: dcmStorageID=retrieve-cache,dicomDeviceName=dcm4chee-arc,cn=Devices,cn=DICOM Configuration,dc=dcm4che,dc=org
    objectClass: dcmStorage
    dcmStorageID: retrieve-cache
    dcmURI: ${jboss.server.data.url}/retrieve-cache/
    dcmDigestAlgorithm: MD5
    dcmExportStorageID: fs1
    dcmProperty: pathFormat={now,date,yyyy/MM/dd}/{0020000D,hash}/{0020000E,hash}/{00080018,hash}
    dcmProperty: checkMountFile=NO_MOUNT
    dcmRetrieveCacheMaxParallel: 10
  

One may refer to Storage Descriptor to understand the description of attributes.

Go to the Control tab on Configuration page in archive UI and reload the configuration.

Testing

Enable the logging in Wildfly configuration to DEBUG mode before starting the tests.

Required dcm4che Tools

• storescu simulating the external object source (e.g. modality) STORESCU, from which objects are being received
• storescp simulating the external object destination (e.g. workstation) STORESCP, to which received objects are forwarded.
• movescu implements both an SCU for the Query/Retrieve Service Class and an SCP for the Storage Service Class.
• getscu implements SCU for the Query/Retrieve Service Class and an SCP for the Storage Service Class.

Tests

• Query Retrieve using C-MOVE and C-GET
• Query Retrieve with Series Metadata
• Query Retrieve after Instance Records Purged
• Retrieve Cache for Export
• Retrieve Cache for RAD-69
• Retrieve Cache for WADO-RS
• Deletion of least recently accessed study from Retrieve Cache
• Deletion of least recently accessed study from Retrieve Cache after Instance Records Purged