Storage Manager, HDD/SDD
Select disk and expand information.
Check Status: Normal
Check S.M.A.R.T status: Normal
Check Bad sector count: 0
Select disk and health info, overview
Disk Reconnection Count, Bad Sector Count and Disk Re-identification Count indicate the total quantity of events that have occurred on your disk or system.
Your data are still safely stored on the disk. Although these parameters provide early warning and information about disk health trends, they do not directly imply imminent disk failure.
Disk Reconnection Count display the sum of S.M.A.R.T. Attribute “UItraDMA CRC Error Count” and other interface issues detected by the system. If this parameter increases abruptly compared to general tendency, it may indicate that the disk or some hardware components are aging.
Select disk and health info, S.M.A.R.T test
Run Quick and Extended test. Check results.
Select disk and health info, S.M.A.R.T info
Use https://en.m.wikipedia.org/wiki/S.M.A.R.T. for reference
check status: OK
01 Read Error Rate:
(Vendor specific raw value.) Stores data related to the rate of hardware read errors that occurred when reading data from a disk surface. The raw value has different structure for different vendors and is often not meaningful as a decimal number.
If you see any non-zero raw values for ID 1 (for WD and Samsung disks) in the disk S.M.A.R.T. info, the disk is defective.
05 Reallocated Sectors Count : 0
09 Power-on Hours:
Count of hours in power-on state. The raw value of this attribute shows total count of hours (or minutes, or seconds, depending on manufacturer) in power-on state.
By default, the total expected lifetime of a hard disk in perfect condition is defined as 5 years (running every day and night on all days). This is equal to 1825 days in 24/7 mode or 43800 hours.
10 Spin Retry Count: 0
184 End-to-End error / IOEDC: 0
187 Reported Uncorrectable Errors: 0
188 Command Timeout: 0
196 Reallocation Event Count: 0
197 Current Pending Sector Count: 0
198 (Offline) Uncorrectable Sector Count: 0
201 Soft Read Error Rate or TA Counter Detected:
According to Synology Support:
If you see any non-zero raw values for ID 1 (for WD and Samsung disks) and ID 5/197/198 (for all disks) in the disk S.M.A.R.T. info, the disk is defective.