iam using ssd for caching other disks ( flashcache module ) if a power failure happened write operations will just stop suddenly and lead to bad sector due to incomplete cache back to devices ( sata disks ) so is there is a way to continue get cache from ssd to devices ( disks ) after server startup, as the cache already stored on ssd?
Many thanks in advance
You need to protect your site/facility power first. Please use an appropriately-sized UPS with enough run time.
Beyond that, I'm an advocate of quality SSDs. You want to use a good SSD with a super-capacitor onboard to protect in-flight data.
If you're asking about general cache persistence, that's another topic.
According to the documentation:
It is important to note that in the first cut, cache writes are
non-atomic, ie, the "Torn Page Problem" exists. In the event of a
power failure or a failed write, part of the block could be written,
resulting in a partial write. We have ideas on how to fix this and
provide atomic cache writes (see the Futures section).
So it sounds like flashcache can't do what you want.
Actually after testing flashcache using write-back cache method i were able to continue getting already stored cache on ssd back to cached disks after power failure or a crash normally using flashcache_load. It looks like the official documentation is outdated.