May 31 2013

Howto: Upgrade Synology Hard Drives to Larger Capacity

Synology DS211j

Recently one of my 2 TB hard drives in Synology broke down. While waiting for the replacement drive to arrive from Sweden, I decided to upgrade my drives from 2 x 2 TB to 2 x 3 TB. If you would also like to replace your hard drives in Synology to bigger ones, here’s how to do it.

Backup Your Data

The most important step in the upgrade process is backing up your existing data. I cannot stress this too much. One good and cheap solution is to buy an external drive of the same or larger capacity than your drive volume in Synology. The data is much faster to duplicate to an external drive connected to your computer or Synology than copy over network. It is also much cheaper than online backup services, such as Amazon Glacier, Crash Plan, Dropbox,, Backblaze or JustCloud. I myself use a Finnish non-profit which among other things (web hosting, shell, databases, etc.) offers backup space for its members. So remember to backup your data before changing hard drive configurations. You have been warned :-).

Replace One Drive & Rebuild Volume

Degraded Volume
Always shut down your Synology when changing hard drive configurations. (OK, some Synologys support hot-swapping, refer to your Synology’s specs.) When I took the defect drive off and put the new bigger drive to its place my Synology DS211j began to beep constantly. It is a normal feature and it is suppose to tell you that there is something wrong with the hard drive configuration (“volume”) and you should do something about it. If you do nothing then you data availability may be compromised. Now you know what you are doing and there is no need for the beep and you can disable it on the admin UI. Login as admin and from the System Menu (upper left corner in Synology DSM 4.2) select Storage Manager. In the Volume tab there is a button “Beep off” (see the screen capture above).

Volume should say “Degraded” and it means One or more hard disks in the volume have failed, but data loss has not occurred. That is perfectly normal because you have not yet configured it to use the newly installed hard drive. The drive itself should say “Not Initialized” which means The hard disk is operating normally, but contains no system partitions or data partitions.

When rebuilding the volume I followed the steps I found in Synology Knowledge Base: How to repair volumes. From the “Storage Manager” select the degraded volume and select “Manage”. Select the first option “Repare” and “Next”. Then choose the newly added drive and “Next”. It will warn you about erasing all of the data on it but it does not matter because it is a new and empty drive anyway so select “OK”. The Volume Manager Wizard will show you the summary of the changes it will make and after checking every thing is OK select “Apply”. It will now show the volume status as “Repairing (initializing)” → “Repairing (Checking parity consistency”) and that takes a while (17 hours in my case). If you have configured email settings properly, Synology will send you two status updates via email “DiskStation has finished checking the consistency on system volume (Root). The system is now ready for use.” The other email is exactly the same except now “Root” is “Swap”: “DiskStation has finished checking the consistency on system volume (Swap)”. However these emails are misleading because it will continue to rebuild the volume even after you will get this notification. Please also note that Synology will not send notification when the rebuild is ready.

Replace the Other Drive & Rebuild Volume

Synology DS211j I found an article in the Synology Knowledge Base: How to Expand Volumes or Disk Groups by Replacing Hard Disks on Synology NAS and I followed the steps written in there. When the rebuilding is done you can take the other, older and smaller drive out and insert the bigger one to its place. Boot Synology up and once again your volume is “degraded” and Synology beeps constantly. It is perfectly normal. Turn the beeping off once again in “Storage Manager”and select “Manage” → “Repair” → “Next”. Then follow the exact same steps in the previous step above. It takes a while again to rebuild the volume so let it run over night.

After the volume rebuilding is done it will enter a new phase: “Repairing (Adding disk)”. This took four hours to complete. Next it will tell you it is “Repairing (Expanding file system)”. This phase completed in one hour. Once it is done, Storage Manager will show the new larger capacity for the volume.

Verify Your Data

As a last step you should verify that the data is intact. I browsed the photos and listened to the music here and there. If everything seems to be there and working, then that’s it, enjoy!

10 Responses to “Howto: Upgrade Synology Hard Drives to Larger Capacity”

  • Adrian Says:

    Thanks for sharing. Very useful.

  • jeremy Says:

    Its time for me to upgrade my DS213 from 2 to 3GB disks so this guide is very helpful, thanks!

  • Victor Says:

    Hi Ari,

    Thank you for your instruction in this post!
    It’s very helpful as I’m about to do a same thing to my DS212j.

    Just a question regarding to the ‘Backup’ step and I’m wondering if you have got the answer to that:

    currently I’ve got 3TB+1TB non-raid combination, surely I’m about to upgrade my 1TB. When performing the backup, do I need to worry about the things on both disk or just the ones on the 1TB?

    In other word, does the action of changing one disk affect the other?

    Thank you so much again!


    • arinium Says:

      Hi Victor,

      Thank you for the comments. So “non-raid” would mean that your data is not duplicated on both disks, right? If so, then changing one should not affect the other. But I don’t know if you have some special Synology setup :). I would backup the data anyway before the operation for example using an external hard drive.


      • Victor Says:

        Hi Ari,

        Thank you for your answer!

        The reason I was asking is that I want to make sure how big the backup drive should I get.

        Anyway, I will back up all and see if it affect the other one.

        Thank you again for your help!


  • Erik Says:

    Good article. Helped me out just fine while changing HD on my Ds212J and got in some problem. Thanks my friend!

  • Henrik Uttrup Says:

    Thank you for a nice explanation! While updating in the blind i found your description. That was very calming even without data-loss as i just resized the disks and had 2 drives without errors.

    Thank you!

  • Jure Says:

    Great articel Ari, thank you.
    Did you hapened to find veryfied info what is the biggest capacity of the drives in DS211j.
    3TB, 4TB or even larger ?

    Thanks for info.

    • arinium Says:

      Hi Jure,

      At least it supports 3 GB because those were my drives :). I cannot tell what is the maximum capacity though.


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