Experiments in Ceph (with Promox)

So, last month, my kubernetes cluster decided to literally eat shit while I was out on a work conference.

When I returned, I decided to try something a tad different, by rolling out proxmox to all of my servers.

Well, I am a huge fan of hyper-converged, and clustered architectures for my home network / lab, so, I decided to give ceph another try.

I have previously used it in the past with relative success with Kubernetes (via rook/ceph), and currently leverage longhorn.

Cluster Details

Kube01 - Optiplex SFF

i7-8700 / 32G DDR4
1T Samsung 980 NVMe
128G KIOXIA NVMe (Boot disk)
512G Sata SSD
10G via ConnectX-3

Kube02 - R730XD

2x E5-2697a v4 (32c / 64t)
256G DDR4
128T of spinning disk.
2x 1T 970 evo
2x 1T 970 evo plus
A few more NVMes, and Sata
Nvidia Tesla P4 GPU.
2x Google Coral TPU
10G intel networking

Kube05 - HP z240

i5-6500 / 28G ram
2T Samsung 970 Evo plus NVMe
512G Samsung boot NVMe
10G via ConnectX-3

Kube06 - Optiplex Micro

i7-6700 / 16G DDR4
Liteon 256G Sata SSD (boot)
1T Samsung 980

Attempt number one.

I installed and configured ceph, using Kube01, and Kube05.

I used a mixture of 5x 970 evo / 970 evo plus / 980 NVMe drives, and expected it to work pretty decently.

It didn’t. The IO was so bad, it was causing my servers to crash.

I ended up removing ceph, and using LVM / ZFS for the time being.

Here are some benchmarks I found online:

https://docs.google.com/spreadsheets/d/1E9-eXjzsKboiCCX-0u0r5fAjjufLKayaut_FOPxYZjc/edit#gid=0

https://www.proxmox.com/images/download/pve/docs/Proxmox-VE_Ceph-Benchmark-202009-rev2.pdf

The TLDR; after lots of research- Don’t use consumer SSDs. Only use enterprise SSDs.

Attempt / Experiment Number 2.

I ended up ordering 5x 1T Samsung PM863a enterprise sata drives.

After, reinstalling ceph, I put three of the drives into kube05, and one more into kube01 (no ports / power for adding more then a single sata disk…).

And- put the cluster together. At first, performance wasn’t great… (but, was still 10x the performance of the first attempt!). But, after updating the crush map to set the failure domain to OSD rather then host, performance picked up quite dramatically.

This- is due to the current imbalance of storage/host. Kube05 has 3T of drives, Kube01 has 1T. No storage elsewhere.

BUT… since this was a very successful test, and it was able to deliver enough IOPs to run my I/O heavy kubernetes workloads… I decided to take it up another step.

A few notes-

Can you guess which drive is the samsung 980 EVO, and which drives are enterprise SATA SSDs? (look at the latency column)

Future - Attempt #3

The next goal, is to properly distribute OSDs.

Since, I am maxed out on the number of 2.5" SATA drives I can deploy… I picked up some NVMe.

5x 1T Samsung PM963 M.2 NVMe.

I picked up a pair of dual-spot half-height bifurcation cards for Kube02. This will allow me to place 4 of these into it, with dedicated bandwidth to the CPU.

The remaining one, will be placed inside of Kube01, to replace the 1T samsung 980 NVMe.

This should give me a pretty decent distribution of data, and with all enterprise drives, it should deliver pretty acceptable performance.

More to come…