Re: [linux-lvm] Question about thin-pool/thin LV with stripes

[Zdenek Kabelac <zkabelac@redhat.com>]

Dne 24. 01. 19 v 15:54 Eric Ren napsal(a):
> Hi,
> 
>     As you can see, only "mythinpool_tdata" LV has 2 stripes. Is that OK?
>     If I want to benefit performance from stripes, will it works for me? Or,
>     should I create dataLV, metadata LV, thinpool and thin LV using
>     step-by-step way
>     and specify "--stripes 2" in every steps?
> 
> 
> With single command to create thin-pool, the metadata LV is not created with 
> striped
> target. Is this designed on purpose, or just the command doesn't handle this 
> case very
> well for now?
> 

Hi

Yes this on purpose currently.

When you create 'thin-pool' - you are mostly specifying options for 'DATA' 
volume. The allocation of metadata is using 'internals' to pick the place
and other properties -  we can maybe introduce some policy option
to make metadata raid1 or striped or something like that.

ATM it's not so easy to do the best possible allocation - so
for skilled admin - it's always most 'secure' to build pool
from bricks - data LV + meta LV.

The automatic allocation will get enhanced over the time - but it's
always somewhere 'fuzzy' what is going to be the results.

Basically - what is 'unspecified' on command line and left for lvm2 to figure 
out - may change between releases - if we consider there is better solution.

Zdenek