function copySliceItem(params, callback) {
    var TaskId = params.TaskId;
    var Bucket = params.Bucket;
    var Region = params.Region;
    var Key = params.Key;
    var CopySource = params.CopySource;
    var UploadId = params.UploadId;
    var PartNumber = params.PartNumber * 1;
    var CopySourceRange = params.CopySourceRange;

    var ChunkRetryTimes = this.options.ChunkRetryTimes + 1;
    var self = this;

    Async.retry(ChunkRetryTimes, function (tryCallback) {
        self.uploadPartCopy({
            TaskId: TaskId,
            Bucket: Bucket,
            Region: Region,
            Key: Key,
            CopySource: CopySource,
            UploadId: UploadId,
            PartNumber:PartNumber,
            CopySourceRange:CopySourceRange,
            onProgress:params.onProgress,
        },function (err,data) {
            tryCallback(err || null, data);
        })
    }, function (err, data) {
        return callback(err, data);
    });
}