Alita's big data computing service is a general-purpose computing engine,which does not limit to a single project like SETIOHomeFolding@Home. Therefore,it is impossible to determine whether miners are honest in providing computing resources by simply verifying the results. Because any user's bug,syntax,upstream data changes,and version will cause changes in the results,and many computing tasks are not idempotent due to data changes. So,Alita does not confirm the work certificate through the result verification but provide PoTA (Proof of Task Accomplishment),which uses the occupied time of memory CPU,storage and bandwidth (VCU),and task code and input data to issue work certificate. Alta's basic storage pS utilizes IPFS which is a protocol,not a complete file system. Using this protocol and networking,we have completed the storage cluster composed of storage copy,fragmentation,addressing,and security,which is more suitable for reading distributed computing tasks. The big data computing is quite special,and you can't use results to measure the authenticity of resource consumption. Any user's bug,syntax,package dependency,and version will cause the results to be inconsistent with expectations,and many computing tasks are not idempotent due to data changes. Therefore,Aita doesn't confirm the work certificate through the result verification,but provide PoTA certificate,and issue the work certificate according to the occupied time of memory CPU and storage (VCU),and task code and input data.