Hi, today I am trying to copy files into array, and when copy job is running the file system is suddenly became read-only. In system log there are lots of BTRFS errors showing up. Seems it is caused by one of my cache disk (sdd1). To avoid any data lost could you please help me what should be my next step?

 

Thanks!

tower-diagnostics-20200224-0715.zip

Cache2 dropped offline, and your cache pool is not redundant:

Feb 24 14:18:04 Tower kernel: ata3: hard resetting link
Feb 24 14:18:10 Tower kernel: ata3: link is slow to respond, please be patient (ready=0)
Feb 24 14:18:39 Tower kernel: ata3: COMRESET failed (errno=-16)
Feb 24 14:18:39 Tower kernel: ata3: limiting SATA link speed to 3.0 Gbps
Feb 24 14:18:39 Tower kernel: ata3: hard resetting link
Feb 24 14:18:44 Tower kernel: ata3: COMRESET failed (errno=-16)
Feb 24 14:18:44 Tower kernel: ata3: reset failed, giving up
Feb 24 14:18:44 Tower kernel: ata3.00: disabled

Check cables to see if it comes back online and then run a scrub.

 

Also, even if you want to use the data in single profile you should make the metadata raid1, and see here for better pool monitoring.

Thank you so much! Good news is that I figure out where the problem is, but the bad news... seems the problem is caused by SSD disk itself, not cables. That means I may lose this cache disk. I think I have to accept the lost (files and appdata?) on this disk. What should be my next step? If I change the cache disk, rebuild the cache pool, will it damage my array's existing data? 

Definitely install the "CA Backup / Restore Appdata" plugin and backup your cache drive regularly! Saved me today.

Yes after this lesson I will definitely install CA Backup / Restore app in my tower... Currently is it safe for me to directly start my array? One cache disk is gone, now I have all my array disks and cache disk1.

Thanks!

It's safe to start but cache likely won't mount and will need to be re-formatted.