最近因存储空间不足的问题，将fastdfs迁移到了另一个挂载盘，遭遇了上面的情况，我跟同事找了很久未找到原因，其实只是因为目录权限未放开。进行chmod 777 <目录>解决。
解决过程，同事查看nginx的错误日志过程中找到的：
[root@localhost logs]# tail -100 error.log
ngx_http_fastdfs_process_init pid=30
[2020-05-22 08:28:39] ERROR - file: ../storage/trunk_mgr/trunk_shared.c, line: 194, "Permission denied" can't be accessed, error info: /var/fdfs/storage
2020/05/22 08:28:39 [alert] 29#0: worker process 30 exited with fatal code 2 and cannot be respawned
ngx_http_fastdfs_process_init pid=36
[2020-05-22 08:42:54] INFO - fastdfs apache / nginx module v1.21, response_mode=proxy, base_path=/var/fdfs/storage, url_have_group_name=1, group_name=group1, storage_server_port=23000, path_count=1, store_path0=/var/fdfs/storage, connect_timeout=2, network_timeout=30, tracker_server_count=1, if_alias_prefix=, local_host_ip_count=8, anti_steal_token=0, token_ttl=0s, anti_steal_secret_key length=0, token_check_fail content_type=, token_check_fail buff length=0, load_fdfs_parameters_from_tracker=1, storage_sync_file_max_delay=86400s, use_storage_id=0, storage server id/ip count=0 / 0, flv_support=1, flv_extension=flv
