NSA325 RAID1 lost

Hello Mijzelf,

This is dmesg log. As you said before I have to investigate it and found the issue

GPT:Primary header thinks Alt. header is not at the end of the disk.
GPT:5860577133 != 7814037167
GPT:Alternate GPT header not at the end of the disk.
GPT:5860577133 != 7814037167

I fixed Primary header but not backup (Alt. header). NAS OS found this ussie and won't start. Both message before about the same: Alt Header is not corresponding with Primary and with the end of the disk (It is rationally to cover all HDD space in GPT).

You are right: a backup GPT header stored at the final LBA, looks like OS found it somehow in sector 5860577133 (3Tb)

So the GPT interpreter here seems to look at a 3TB disk having a 4TB GPT, or vise versa.

IDK how is it working and actually I have only common understanding of GPT.

I have only one explanation: 5 december I fixed Primary header and initial size (4tb) was restored (confirmed by TestDisk screenshot). It had correct information about Max LBA. Now interpreter could look at Secondary Header and may be he found an incorrect addres about size in SecHeader