NAS server · Tips & Tricks

Protect your data with Synology Data Scrubbing

What is data scrubbing?

First of all, what is data scrubbing?

Data scrubbing is a data maintenance feature that inspects storage pools looking for corrupt data and repairing it.

Still a bit unclear right? Let me show you with an example.

You go into your synology to retrieve one of your summer pics and while you expect to see the left image, you find yourself with the one on the right. Not fun right?

data corruption
Source: https://blog.synology.com/how-data-scrubbing-protects-against-data-corruption/

The worst part of all is that once your data is corrupted, it can get worst with time.

What can cause your data to become corrupt?

Here are some examples:

  1. Improper system shutdowns
  2. System crashes or freezes,
  3. Hard drive failures, bad disk sectors,
  4. Virus infections..

Synology data scrubbing

Synology offers two types of Data Scrubbing:

  • RAID scrubbing: This function can be used with storage pools that implement SHR (comprised of three or more drives), RAID 5, or RAID 6. It can repair any detected data inconsistencies.
  • File system scrubbing: This function will check the volumes in Btrfs file system. If any data inconsistent is detected, the system will try to use a backup to repair the data and the file path will be recorded in Log Center.

Why does Synology offer two types of data scrubbing?

RAID scrubbing can ensure data consistency but it cannot tell which data block is incorrect but Btrfs data scrubbing does exactly that. AND, you do not need to choose between the two, you can have both 🙂

If you are curious and want to know exactly how both works, you can do it here.

How often should I perform Synology data scrubbing?

First of all, you should regularly performe Data Scrubbing to ensure data consistency and avoid data loss in the event of drive failure, but how often should you do it?

….

and you guessed it right, it depends. I can never give you a straight answer 🙁 but I can give you a roadmap.

Data scrubbing will add addtional stress to your disks and possibly performance, so you need to take that into account when configuring data scrubbing. Do like this:

  1. Run some to see how your synology performs while doing it
  2. Check how long it takes

and then decide how often you should run it:

  1. If it doesnt take too long and it doesnt affect performance, you can run it often (wouldnt go under once a week)
  2. If it affects performance, but doesnt take too long, schedule it when the server is less used.
  3. If a full scan takes over a week, consider doing it every other month.

Take also into account that the older the disks, the higher the risk of failure if you run it too often.

Synology data scrubbing limitations

  • Data Scrubbing and the related functions described in this article are available on specific models only.
  • Data Scrubbing cannot be performed when the status of the storage pools is Crashed or Degraded.
  • If data checksum for advanced data integrity is not enabled for a shared folder, file system scrubbing will not be able to check and repair the data in the folder for lack of checksums.
  • To add a schedule, the storage pool has to be in Normal status and supports Data Scrubbing.
  • If your system is upgraded from version 6.1, storage pools with the capability of running Data Scrubbing will by default be added to the schedule.
  • If you have set your schedule in version 6.1, we will automatically enable your schedule according to your previous settings.
  • A storage pool cannot be added to or removed from a schedule when Data Scrubbing is being manually run on this storage pool.
  • To remove a storage pool that is undergoing a scheduled Data Scrubbing, the progress of this storage pool will be canceled.
  • Modifying the Start date will reset the progress of the schedule and Data Scrubbing will be restarted according to the new start date.
  • You need to click Resume Schedule from the Action drop-down menu to resume a Data Scrubbing schedule. Otherwise, the schedule will remain paused.
  • If the system is shut down before Data Scrubbing completes, some progress may be lost and you will need to manually restart Data Scrubbing.
  • If the time of manually-run Data Scrubbing overlaps with the scheduled Data Scrubbing, this round of schedule will not be completed until manually-run Data Scrubbing is finished.
  • Running Data Scrubbing may influence your system performance, we suggest you not to run Data Scrubbing on multiple storage pools unless it is necessary.

Ok, I am in, how do I configure Synology Data Scrubbing?

That is the easy part, do like this:

  1. Launch Storage Manager.
  2. Go to Storage Pool > Data Scrubbing.
  3. Click Set schedule.
  4. Tick Enable Data Scrubbing schedule.
  5. Specify the Frequency, Start date, and Time Session.
  6. Go to Select Target tab.
  7. Select the storage pool on which you want to perform Data Scrubbing.
  8. Click OK.

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