[DRBD-user] DRBD on virtual machine

Pascal BERTON pascal.berton3 at free.fr
Wed Feb 18 11:48:11 CET 2015

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Hi Antonio !


As far as I know, virtio is the IO layer of KVM. In your case you’re planning to use ESXi, so I believe you may disregard that point.

However, as Cesar said, performance will be key. So take care to implement the most performant paravirtualized drivers within your VMs, namely vmxnet3 and pvscsi (But if your distro is recent, that will the case by default), and it probably would also be a good idea to put your replication network on dedicated vSwitch, with dedicated vmnics, to avoid bandwidth sharing.

There’s also a feature within ESXi that’s called “VM Direct Path IO”, I think it’s standard, you don’t have to pay for it, that consists of dedicating a piece of hardware to some VM, might be a card, a port... In this case, you have to install the corresponding driver into the guest OS, and you forget vmxnet3, at least for this replication link(s). There are 2 advantages : 1) You ensure bandwidth dedication to these VMs 2) You avoid VMkernel virtualization overhead. This maximizes performances. I know Telco guys that used that with 10GbE cards to achieve their perf requirements. If you use that however, your VM will be tied to its ESXi, you won’t be able to migrate it on another host, but from the DRBD prospective, I don’t guess it’s a big deal for your clustering is “at the DRBD level” if I may say…


Hope this helps!


Best regards,




De : drbd-user-bounces at lists.linbit.com [mailto:drbd-user-bounces at lists.linbit.com] De la part de Antonio Fernández Pérez
Envoyé : mercredi 18 février 2015 11:20
À : Cesar Peschiera
Cc : drbd-user at lists.linbit.com
Objet : Re: [DRBD-user] DRBD on virtual machine


Hi list:


Thanks for your replies.


I will have MySQL on these two servers. On our environment there are a lot of read/write transactions so speed is very important for perform everyday actions.


I don't understand when you say about virtio-block and virtio-net. What is that? Some configuration method for VM?

What do you want to say when you speak about host and guest? I think that an iESX has a lot of VM and a VM is a ¿guest? What is the "host"?


Thanks for your suggestions.


Thanks in advance.





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