[pve-devel] [PATCH storage] rbd: add support for erasure coded ec pools

[Aaron Lauterer]

On 1/26/22 19:30, Alwin Antreich wrote:
> Hello Aaron,
> 
> nice to see EC pools are coming. ;)
> 
> January 26, 2022 5:07 PM, "Aaron Lauterer" <a.lauterer at proxmox.com> wrote:
> 
>> The first step is to allocate rbd images correctly.
>>
>> The metadata objects still need to be stored in a replicated pool, but
>> by providing the --data-pool parameter on image creation, we can place
>> the data objects on the erasure coded (EC) pool.
> 
> AFAICR, there is an undocumented location for a ceph.conf,
> `/etc/pve/priv/ceph/<storage-name>.conf`.

Thanks for the hint, as I wasn't aware of it. It will not be considered for PVE managed Ceph though, so not really an option here.[0]

[0] https://git.proxmox.com/?p=pve-storage.git;a=blob;f=PVE/CephConfig.pm;h=c388f025b409c660913c082763765dda0fba2c6c;hb=HEAD#l192

> 
> The config should have the following content.
> ```
> [client.admin_ec]
> rbd default data pool = ceph_pool_ec
> ````
> Then rbd will use the data pool. This should probably work for all storage operations.
> 
> Newer ceph versions should also work with the config db option.
> ```
> ceph config set client.xxx rbd_default_data_pool ceph_pool_e> ```

What these approaches do have in common, is that we spread the config over multiple places and cannot set different data pools for different storages.

I rather keep the data pool stored in our storage.cfg and apply the parameter where needed. From what I can tell, I missed the image clone in this patch, where the data-pool also needs to be applied.
But this way we have the settings for that storage in one place we control and are also able to have different EC pools for different storages. Not that I expect it to happen a lot in practice, but you never know.

> 
> Cheers,
> Alwin
> 
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