[SOLVED] How to set Ceph - # of PGs? - Keeps falling back to 32.

[kez]

Hi,

I'm not sure how, but my Ceph was set to (# of PGs: 32). I found this while investigating slow disk speed on VMs.

From the docs:

When no options are given, we set a default of 128 PGs, a size of 3 replicas and a min_size of 2 replicas, to ensure no data loss occurs if any OSD fails.

I've changed my PGs in PVE GUI to match the docs 128 PGs, Ceph starts to rebalance, and the PGs start to fall again. It's back down to 32 now:

How do I get it to 128 as per the guide? https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_pool_options and screenshot from guide:

Is it as simple as using the (Min. # of PGs)? It's just that is not in the guide or screenshots.

Its a simple 4 node cluster each with 1 disk.

Thanks.

 

[kez]

Setting the ratio to 1 seems to have set the PGs to 128. As it's the only pool, I think ratio 1 is correct.

 

[jsterr]

You could have also set # of pgs to 128 and minimum # of pgs to 128 as well.

 

[SteveITS]

Ceph has an autoscaler feature. How much space is used in it?

Re ratios, FWIW in my experience it seems to ignore target size if ratio is blank, so use ratio.