There are many factors affecting performance, please follow the steps below to check further.
1. Make sure whether there is any problem about network connection (try to replace network cable, or port on switch or router). Besides, also check whether other network device has the same problem.
2. Check disk status. You can check its S.M.A.R.T information via web UI
3. Check RAID status. If its status is degraded or rebuilding, please wait for completion and it gets back to normal.
4. Check whether there are many users accessing the SJC at the same time
If you have followed the steps above to check but still faced the same performance problem, please provide the information below so that we can analyze further.
1. How did you connect to SJC (via CIFS,FTP,AFP, or remote access)? Also, please provide your network connection topology.
2. Which platform and OS version did you use (Window/Mac) ? Please provide your RAM size and disk model used for your platform.
3. How did you test it (If you use test performance tool, please provide its information and parameters you set on it)
4. The screenshot about the performance when you access or test