[linux-lvm] LVM and HSM?

Gionatan Danti g.danti at assyoma.it
Mon May 13 17:24:50 UTC 2019

Il 13-05-2019 10:26 Zdenek Kabelac ha scritto:
> Hi
> There is no technical problem to enable caching of cached volume (aka
> convert cache_cdata LV into another 'cached' volume.
> And as long as there are not errors anywhere - it works.
> Difficulty comes with solving error cases - and that's the main reason
> it's not enable so far.
> So I don't see big issue with enabling usage on 'user's own risk'.

Hi, how "cache of cached volume" is tiered/hierarchical storage?
In such a case, total available space is the sum of all storage 
hierarchy. For example, using 1 TB SSD + 8 TB HDD would result in 9 TB 
total in a tiered/hierarchical case, while "only" 8 TB on a cached 

Am I missing something here?

The interesting thing is that LVM already supports something similar to 
tiered storage, as pvmove can be used to migrate hot physical extent to 
faster devices. The hard/manual thing is to determine *which* extent to 


Danti Gionatan
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