Le Thu, 14 Sep 2017 11:46:11 -0300
FERNANDO FREDIANI [off-list ref] écrivait:

Not really mandatory but optional.

From bcache documentation:

"In the event of a data IO error on the flash it will try to recover
by reading from disk or invalidating cache entries.  For
unrecoverable errors (meta data or dirty data), caching is
automatically disabled; if dirty data was present in the cache it
first disables writeback caching and waits for all dirty data to be
flushed."

If the cache is dirty and has failed, your data is lost or corrupted
all the same. The way a SSD fails is usually one second it works, the
next second it's as dead as a rock. If you're using it as a write
cache, whatever amount of data is dirty is lost. If it's 8 GB, you've
lost your last 8 GB of writes, often very important filesystem metadata
and/or database journal, i.e. your data is completely hosed.

Don't use SSDs as write cache without RAID-1 (or use very expensive,
redundant NVMe SSDs only), unless your data isn't very important.

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