[linux-lvm] Why doesn't the lvmcache support the discard (trim) command?

[Gionatan Danti]

On 19/10/2018 12:58, Zdenek Kabelac wrote:
> Hi
> 
> Writecache simply doesn't care about caching your reads at all.
> Your RAM with it's page caching mechanism keeps read data as long as 
> there is free RAM for this - the less RAM goes to page cache - less read 
> operations remains cached.

Hi, does it mean that to have *both* fast write cache *and* read cache 
one should use a dm-writeback target + a dm-cache writethrough target 
(possibly pointing to different devices)?

Can you quantify/explain why and how faster is dm-writeback for heavy 
write workload?

Thanks.

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Danti Gionatan
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