Ceph – Create custom CRUSH rules for SSD Not Working

[Bilal]

I want to build 3 server nodes Proxmox HCI Cluster

Server Nodes :2x Dell Poweredge 730 & 1x Dell Poweredge R430
NIC : 2x 10 Gigabit for ceph and 2x 1gig NIC in each node
Storage : 4x 1TB Read Intensive SSDs in each node (1 for Proxmox OS and 3 for cache)
Recently added New Storage : 3x 8TB SATA HDD for Storagein each node

Now i want to maje seperate pool of SSDs for cache and HDDs for Storage
But commadn $ceph osd tree shows that all disk types are HDD including my SSD disk

This command gives error
ceph osd crush rule create-replicated ssd-only default osd ssd

Error EINVAL: device class ssd does not exist

 

[Alwin]

See our docs, for device class based pools. You can set the device class for SSDs manually too. Ceph tries to find the the class, but fails if they are masked, for example by a RAID controller.
https://pve.proxmox.com/pve-docs/chapter-pveceph.html#pve_ceph_device_classes

 

[Bilal]

Bundle of Thanks Alwin , It works ..... Can you please recommend me one more thing i have 4x 8TB HDDs on each of the 3 nodes. Please guide that 3x 1TB SSD on each node will be sufficient for cache in ceph cluster?

 

[Alwin]

It will improve the speed/latency of an OSD. But I can't tell you if it will be sufficient for your use case.