| 1 | ### Understand the alert |
| 2 | |
| 3 | This alert presents the number of unsynchronized blocks for the RAID array in crisis. Receiving this alert indicates a high number of unsynchronized blocks for the RAID array. This might indicate that data on the array is corrupted. |
| 4 | |
| 5 | This alert is raised to warning when the metric exceeds 1024 unsynchronized blocks. |
| 6 | |
| 7 | ### Troubleshoot the alert |
| 8 | |
| 9 | There is no standard approach to troubleshooting this alert because the reasons can be various. |
| 10 | |
| 11 | For example, one of the reasons might be a swap on the array, which is relatively harmless. However, this alert can also be triggered by hardware issues which can lead to many problems and inconsistencies between the disks. |
| 12 | |
| 13 | ### Useful resources |
| 14 | |
| 15 | [Serverfault | Reasons for high mismatch_cnt on a RAID1/10 array](https://serverfault.com/questions/885565/what-are-raid-1-10-mismatch-cnt-0-causes-except-for-swap-file/885574#885574) |