On 28/08/2020 18:25, Ram Ramesh wrote:
I am mainly looking for IOP improvement as I want to use this RAID in
mythtv environment. So multiple threads will be active and I expect
cache to help with random access IOPs.
???
Caching will only help in a read-after-write scenario, or a
read-several-times scenario.
I'm guessing mythtv means it's a film server? Can ALL your films (or at
least your favourite "watch again and again" ones) fit in the cache? If
you watch a lot of films, chances are you'll read it from disk (no
advantage from the cache), and by the time you watch it again it will
have been evicted so you'll have to read it again.
The other time cache may be useful, is if you're recording one thing and
watching another. That way, the writes can stall in cache as you
prioritise reading.
Think about what is actually happening at the i/o level, and will cache
help?
Cheers,
Wol
