Metadata on flash / fusion pools

[brettyj]

Hey,

Can't seem to find an answer to this. Will this only apply to new pools that are set up as fusion pools from the beginning, or can you add flash vdevs to an existing pool at a later date?

I'd love to have the option to add ssds at a later date, don't need them at the moment.

Thanks

 

[Ericloewe]

It only applies to new writes, so usefulness is limited.

 

[brettyj]

That's a shame, would be good if we could run some process to move metadata from the HDDs to the SSD, having to move the entire pool off and then back on is a massive PITA.

 

[Yorick]

if we could run some process to move metadata from the HDDs to the SSD

Local replication, assuming you are low on utilization. Replicate to a new dataset once the special allocation vdev is in, delete old dataset.

No need to do that for files that receive writes. Anything that gets touched frequently will have its metadata moved on first write.

 

[brettyj]

Ah that's cool, and worth knowing :) Thanks!