[SOLVED] Ceph & iSCSI HA - How to configure the network?

Dec 21, 2019
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I am looking to some guidance to finalize the setup of a 3-nodes Proxmox cluster with Ceph and shared ISCSI storage. While it's working, I am not really happy with the ceph cluster resilienc and I am looking for some guidance.

Each nodes have 2x10GbE ports and 2x480GB SSD dedicated for ceph (+2x256 NVME storage for the system and other things). The NAS has 1 10GbE and 2x5GbE ports (+2 1GbE) . Following some past discussion I have setup for now the following:

  • 2 distincts networks using 2 mikrotik CRS312-4C+8XG-RM switches with a great total non-blocking throughput of 120 Gbps, switching capacity of 240 Gbps and forwarding rate of 178 Mpps
  • The ceph d network only goes over 1 switch in 1 subnet
  • 2x5Gbe ports of the NAS are connected to 1 switch while the the 10GbE port is connected to the other
  • I am using a MULTIPATH session for iSCSI on each nodes.

IMG_0354-2.png

What is not on the picture is the backup server connected to each switch with 1 10GbE link that is supposed to also use the iSCI storage. Unfortunately I can't grow its storage that much since it has only 2x240GB SSD disks (2"5), except maybe by using USB3.


The issue with the design above is that while for iSCSI 2 different networks are really used, the CEPH network is only on one switch

Can we have the ceph network working on 2 different network using VLANs for the same OSDs/monitor nodes etc? I didn't find a way to do it in the web UI but maybe on the command line?

Also should I distinct the iscsi network from the ceph network and put them in distinct vlan?


Any hint/feedback is welcome :)
 
Last edited:
Dec 21, 2019
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a couple more questions.

For now each nodes as I said has 2x256GB nvme M2 disks and 2x480GB SSD used foir ceph. the M2 card is using the only PCiE3.0 x8 possible extension. I am wondering I one better way to handle what I need woul dbe replacing this M2 card by 1 network card to extend the number of 10GB ports and replace the system disk by 1 NVME. and later replace the 480 GB disks by 1TB disks Thoughts?

Also I can probably use such extension to reuse the m2 disks : https://www.qnap.com/fr-fr/product/qda-a2mar

If I don't change the configuration, I am wondering if usiing LAG between the 2 switches and vlans would work?
 
Last edited:

Alwin

Proxmox Staff Member
Staff member
Aug 1, 2017
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For Ceph you will need to create a bond. Or a switched setup with STP and a path cost.
 

Alwin

Proxmox Staff Member
Staff member
Aug 1, 2017
4,617
433
88
You mean bonding between 2 switches and bonding between each interfaces?
I meant the interfaces, a LAG between the switches OFC wouldn't help.

should I balance the traffic or use a an active-backup strategy?
When two different switches are involved, then you may better use active-backup. Other modes will need further configuration on the switches.
 
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