[linux-lvm] How to calculate the LVM SSD cache size?

[Kees de Jong]

Hi,



The documentation is not clear about how big the cache size should be
for optimal performance. It only gives pointers about how big the meta
data for the cache should be.

"Create the cache metadata LV. This LV will hold cache pool metadata.
The size of this LV should be 1000 times smaller than the cache data
LV, with a minimum size of 8MiB."

There is however an example in the man page with a 100GB OriginLV
which apparently needs (at least) 10GB of cache size. But what is the
math? I for example have 4 LV's I want to cache. 6GB, 60GB, 100GB and
2TB and I have a 240GB SSD which will act as the caching disk.

Could someone please fill in the gaps here?




Thanks!
Kees.