My Synology Says a Drive Has Bad Sectors: Should I Replace It?
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Synology gives no bad sector count at which to replace a drive. On DSM 7.2.1 or later, it says to judge by the drive status in Storage Manager > HDD/SSD, and it suggests replacing the drive if it enters Critical status. A stable count means keep monitoring; Synology says only a sharp increase is a cause for concern.
Check your situation
Safe steps
These actions can lose data. Do none of them until a copy exists elsewhere:
- Data written to a bad sector is usually lost, Seagate says, even when a spare sector built into the drive takes its place.
- A full zero fill with Seagate's SeaTools Bootable erases all data on the drive's partitions.
- Repairing a storage pool erases all existing data on the replacement drive.
- On a pool without data protection, Synology's replacement steps create a new storage pool and volume and then restore from backup. Back up all data before you power off.
- Removing the wrong drive from the NAS by mistake.
- If the storage pool's status becomes Crashed, Synology says you can no longer repair it yourself.
- Toshiba says you must back up your data before seeking warranty service, and that Toshiba is not responsible for lost data.
- Back up all your data before you test, swap or repair anything.[1]
- Check your email and the DSM desktop notifications for Number of bad sectors increased or similar alerts.[1]
- Run data scrubbing twice a year, as Synology recommends, to keep data consistent if a drive fails.[1]
- Use Locate Drive before you pull a drive. It switches the drive indicator colour so you remove the right one.[2]
- If your NAS does not support hot-swapping, power it off before you remove or install any drive.[6]
What to buy, if anything
Answer the questions under "Check your situation" and this section narrows to what your case calls for. Until then every table is shown, each with the case it is for.
Replacement NAS drives by price per TB
Why this is here: A replacement for a drive that Synology now shows as Critical, or whose bad sector count is rising fast, bought only after the data is backed up and the old drive's warranty is checked. Confirm the model is on Synology's compatibility list for your NAS and is at least as large as Synology's repair rule for your pool requires. New 3.5-inch NAS and enterprise hard drives whose maker confirms CMR recording, sorted by price per TB on Amazon.com.
Frequently asked questions
Why do I get no bad sector warnings at all?
The bad sector warning is a setting, available on certain models only: Storage Manager > HDD/SSD > Settings > Advanced, select Enable bad sector warning, then Apply. NVMe SSDs do not support it.
Is there a S.M.A.R.T. threshold for bad sectors?
Synology lists bad sector count among the common S.M.A.R.T. attributes and sends warnings when an attribute exceeds the threshold set by the drive's manufacturer. Synology's page states no threshold values.
My monthly health report shows a bad sector count above 0. What now?
That section of the report applies only to DSM 7.2 and below. Synology says a value other than 0 means events were detected, often linked to the environment or connections, and to make sure the drive is securely installed and the NAS is on a stable surface.
Sources
- Synology: There is an increase in my drive's bad sector count. What can I do? checked 2026-10-14
- Synology DSM 7.4 Help: HDD/SSD checked 2026-10-14
- Synology: I received my monthly drive health report. Is there anything I should check for? checked 2026-10-14
- Synology: Frequently asked questions about S.M.A.R.T. test checked 2026-10-14
- Synology: Drive errors occurred, but I am not sure if they resulted from the drives or the drive slots checked 2026-10-14
- Synology DSM 7.4 Help: Repair a Storage Pool checked 2026-10-14
- Seagate: What do I do if my drive reports bad sectors? checked 2026-10-14
- Seagate: Warranty & Replacements checked 2026-10-14
- Western Digital: Warranty policy checked 2026-10-14
- Toshiba: Warranty Return Procedure - HDD checked 2026-10-14
Facts on this page were reviewed on October 14, 2026. Prices and stock are from Amazon.com as of October 14, 2026.