Is a PCI-E SSD-based journal still worth it with Ceph Luminous?

[lucaferr]

Hi! Thanks to a discussion on another thread today I digged into the Ceph Luminous changelogs. If I understood correctly (please correct me if I'm wrong or if this is not applicable to pveceph) Ceph 12 will have the new storage engine called Bluestore enabled by default instead of XFS and writes will work much differently than in the older versions. Since I'm planning to buy 3 new servers to build a PVE 5 and Ceph 12 based cluster I was thinking about spinning disks plus one Intel DC P3700 PCi-E for every node to speed up the journal (and so the writes). Is this still valid with Ceph 12? These SSD are expensive, so I'd buy them only if I get a sensible performance improvement...
Thank you!

 

[tom]

Good question. Ceph 12 is neither production ready, nor do anyone have big experience with the new bluestore. We expect a first release candidate of 12 soon, and we will build immediately packages for Proxmox VE 5.x for testing.

So if you have to deploy the next weeks, you should probably not consider bluestore, at least I would only deploy well known and proofen setups.

 

[dietmar]

But I am quite sure that it is still worth to use an SDD Journal if you plan to use spinning disks.