RAID5 synchronisation is very very slowy

[tchris]

Hello,

I am a new TNAS user. I bought a NAS F6-424. I installed 4 hard disks of 8Tb (ST80000DM4), in a RAID5 array.

The array synchronization is very very very slow. Synchronization does not exceed 1 Mb/s (1000 kb/s). Synchronization reached 6.5% in 8.5 hours.
I used the guide to speed up synchronization and made customizations like viewtopic.php?p=45081&hilit=raid+5+speed#p45081 . This does not affect synchronization speed. System load does not exceed 65%. I didn't run any other applications.

These disks were previously used in a ZFS file system.

I don't understand why synchronization is so slow. Do you have any ideas or tips? Thanks

[TMzethar]

Please confirm the specific model of your Seagate Barracuda drive. While many 8TB Barracudas are now CMR, there is still a possibility that some are SMR. SMR is not suitable for RAID parity mechanisms and could cause issues.
Additionally, I recommend testing the read and write performance of each drive.

[tchris]

Hello,

The 4 disks are ST80000DM004-2CX188. I dont know if they are CMR or SMR.

[Gremlin]

Hello,

The 4 disks are ST80000DM004-2CX188. I dont know if they are CMR or SMR.

I believe they are SMR.

[tchris]

Hello,
I find the information. My disks are SMR. Damned...
Barracuda (https://www.seagate.com/fr/fr/products/cmr-smr-list/).

With SMR disk, what is the best solution ?

[TMzethar]

SMR may not be the only factor; we still recommend that you check your drives. Generally, SMR drives can still be used for non-RAID storage types, such as Single and JBOD. However, considering the nature of the Barracuda drives and the lack of RAID redundancy, it is advisable to regularly back up important data.

[tchris]

Thanks a lot.

[Herewerare2024]

SMR could be used as a video surveillance drive. Also could be a picture/file drive with manual backup to a secondary drive. You could also setup a cronjob to check a master disk and compare to a shadow disk... copy the differences.