On Thu, 25 Mar 2021, at 05:29, Coly Li wrote: > On 3/25/21 4:21 AM, Nikolaus Rath wrote: > > Hello, > > > > My (writeback enabled) bcache cache device had a temporary failure, but seems to have fully recovered (it may have been overheating or a loose cable). > > > > From the last kernel messages, it seems that bcache tried to flush the dirty data, but failed, and then stopped the cache device. > > > > After a reboot, the bcacheX device indeed no longer has an associated cache set.. > > > > I think in my case the cache device is in perfect shape again and still has all the data, so I would really like bcache to attach it again so that the dirty cache data is not lost. > > > > Is there a way to do that? > > > > (Yes, I will still replace the device afterwards) > > > > (I am pretty sure that just re-attaching the cacheset will make bcache forget that there was a previous association and will wipe the corresponding metadata). > > > > Hi Nikolaus, > > Do you have the kernel log? It depends on whether the cache set is clean > or not. For a clear cache set, the cache set is detached, and next > reattach will invalidate all existing cached data. If the cache set is > dirty and all existing data is wiped, that will be fishy.... Hi Cody, I'm not sure I understand. I believe there is dirty data on the cacheset (it was effectively disconnected in the middle of operations). Also, if it wasn't dirty then there would be no need to re-attach it (all the important data would be on the backing device). On the other hand, after a reboot the cache set shows up in /sys/fs/bcache - just not associated with any backing device. So I guess from that point of view it is clean? The kernel logs are on the affected bcache, and I have avoided doing anything with it (including mounting). I took a few pictures of the last visible messages on the console before re-booting though. For example, here is when the problem starts First ATA errors: https://drive.google.com/file/d/1_vr-JBWZjajzbWyXUSmtn4faNH6072ut/view?usp=sharing First bcache errors: https://drive.google.com/file/d/1XLCWDi6G2lP1JiVitZTtIqzB4QqxXv2-/view?usp=sharing Does that help? Best, -Nikolaus -- GPG Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F »Time flies like an arrow, fruit flies like a Banana.«
