Ceph librbd vs krbd

librbd and krbd are just two different clients, the ceph pool does not care much with which one you access an RBD image.

In Proxmox VE we use librbd for VMs by default and krbd for Containers.
But, you can enforce the use of the kernel RBD driver also for VMs if you set "krbd" on in the PVE storage configuration of a pool.

Differences between two clients are:
librbd adopts the use of newer storage features quicker, but with the current 5.4 based kernel you got all good features in the kernel client too.
It's said that KRBD is often a bit faster than librbd, but in my experience librbd isn't slow either and you'd need quite the fast ceph to see a difference.
 
Hi All,

We just experienced a bug that caused us to switch to krbd.

Is there a good reason to switch back once the bug is resolved? It seems that krbd might be faster and I don't see any features that I'm giving up.

best,

James
 
Binary Bandit said:
Hi All,

We just experienced a bug that caused us to switch to krbd.

Is there a good reason to switch back once the bug is resolved? It seems that krbd might be faster and I don't see any features that I'm giving up.

best,

James
Click to expand...
Also did the switch. Nothing to complain about so far. I guess krbd is the way to go.
 
ermanishchawla said:
Can someone explain for my VM setup, I should use librdb or krbd while creating ceph pool
Click to expand...

Hi,
We tried to do a benchmark for Mysql windows server with a huge database on it using a very heavy query (join, left join, group by ecc...)

Here the results:
test n.1 , RBD, queryA ==> 8:34
test n.2 , RBD, queryA ==> 4:12
test n.3 , RBD, queryA ==> 4:03
test n.3 , RBD, queryA ==> 4:24

test n.1 , KRBD, queryA ==> 10:23
test n.2 , KRBD, queryA ==> 6:41
test n.3 , KRBD, queryA ==> 6:29
test n.3 , KRBD, queryA ==> 6:32

The VM has every kind of optimization:
Cache: Write back
Discard: yes
IO thread: yes
SSD emulation: yes
Hard Disk: iSCSI
 
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