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

[Zdenek Kabelac]

Dne 24. 01. 19 v 16:06 Eric Ren napsal(a):
> Hi,
> 
>     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?
> 
>     My main concern here is, if the metadata LV use stripped target, can
>     thin_check/thin_repair tools work fine?
> 
> 
> In our use scenario, we want to use DM thinp for a lot of containers as 
> rootfs. The container use heavy on snapshots,
> so above 4K thin/snapshots LVs may share the thin pool concurrently.
> 
> This may make the space fragmented. So, another concern is, will using striped 
> thinp make
> fragmentation much more worse?

Hi

When 'stripe_size' is the 'right size' - striped device should appear faster,
but telling you what's the best size is some sort of 'black magic'  :)

Basically - strip size should match boundaries of thin-pool chunk sizes.

i.e. for thin-pool with 128K chunksize -  and 2 disks -
I'd assume best result you should get with 64K stripesize (so 2 disks will 
make it 128K stripe)  - but it depends on number of hw aspects.

So you will need to benchmark it.

Zdenek