Find the time left on a Synology rebuild or expand job

While the DSM GUI will give you a rough idea of time needed for a typical rebuild with a percent graph and a little middle school math – getting the estimated time takes only a few commands from the command line.

First Рmake sure you can connect to your NAS over SSH-you can read the whole thing from Synology in the Knowledge Base or:

  1. Log in to the web GUI with an admin account
  2. Go to Network Center > Administration > Service > Terminal.
  3. Tick Enable SSH service.
  4. Specify the desired port for the SSH service. (The default port is 22.)
  5. Click Apply.

Now for the easy part – use PuTTY or your favorite SSH client and log in to your NAS and at the command line enter:

cat /proc/mdstat

You should see a listing of all the Synology devices – most of which are internal and not helpful for what we’re doing here – but you should see one that has the words “recovery = 52% (XXXXXX / XXXXX) finish=2880.4 min” For our expansion of adding another 4 TB drive into the Synology Hybrid Raid, we had an initial finish time of 3250 minutes (2 days, 8 hours) and used this technique to keep tabs on the progress.