On Wed, Apr 16, 2014 at 1:47 AM, Markus Jais wrote:
> thanks. How many nodes to you have running in those 5 racks and RF 5? Only
> 5 nodes or more?
>
While I haven't contemplated it too much, I'd think the absolute minimum
would be RF=N=5, sure. The "real minimum" with headroom would depend on
w
Hi Rob,
thanks. How many nodes to you have running in those 5 racks and RF 5? Only 5
nodes or more?
Markus
Robert Coli schrieb am 20:36 Dienstag, 15.April 2014:
On Tue, Apr 15, 2014 at 6:14 AM, Ken Hancock wrote:
>
>Keep in mind if you lose the wrong two, you can't satisfy quorum. In a 5-no
It is not common, but I know of multiple organizations running with RF=5,
in at least one DC, for HA reasons.
-Tupshin
On Apr 15, 2014 2:36 PM, "Robert Coli" wrote:
> On Tue, Apr 15, 2014 at 6:14 AM, Ken Hancock wrote:
>
>> Keep in mind if you lose the wrong two, you can't satisfy quorum. In a
On Tue, Apr 15, 2014 at 6:14 AM, Ken Hancock wrote:
> Keep in mind if you lose the wrong two, you can't satisfy quorum. In a
> 5-node cluster with RF=3, it would be impossible to lose 2 nodes without
> affecting quorum for at least some of your data. In a 6 node cluster, once
> you've lost one no
Hi Ken,
thanks. Good point.
Markus
Ken Hancock schrieb am 15:15 Dienstag, 15.April 2014:
Keep in mind if you lose the wrong two, you can't satisfy quorum. In a 5-node
cluster with RF=3, it would be impossible to lose 2 nodes without affecting
quorum for at least some of your data. In a 6 n
Keep in mind if you lose the wrong two, you can't satisfy quorum. In a
5-node cluster with RF=3, it would be impossible to lose 2 nodes without
affecting quorum for at least some of your data. In a 6 node cluster, once
you've lost one node, if you were to lose another, you only have a 1-in-5
chanc
Hi all,
thanks for your answers. Very helpful. We plan to use enough nodes so that the
failure of 1 or 2 machines is no problem. E.g. for a workload to can be handled
by 3 nodes all the time, we would use at least 5, better 6 nodes to survive the
failure of at least 2 nodes, even when the 2 nod
tl;dr make sure you have enough capacity in the event of node failure. For
light workloads, that can be fulfilled with nodes=rf.
-Tupshin
On Apr 14, 2014 2:35 PM, "Robert Coli" wrote:
> On Mon, Apr 14, 2014 at 2:25 AM, Markus Jais wrote:
>
>> "It is generally not recommended to set a replicatio
On Mon, Apr 14, 2014 at 2:25 AM, Markus Jais wrote:
> "It is generally not recommended to set a replication factor of 3 if you
> have fewer than six nodes in a data center".
>
I have a detailed post about this somewhere in the archives of this list
(which I can't seem to find right now..) but br
With 3 nodes, and RF=3, you can always use CL=ALL if all nodes are up,
QUORUM if 1 node is down, and ONE if any two nodes are down.
The exact same thing is true if you have more nodes.
-Tupshin
On Apr 14, 2014 7:51 AM, "Markus Jais" wrote:
> Hi all,
>
> thanks. Very helpful.
>
> @Tupshin: With
Hi all,
thanks. Very helpful.
@Tupshin: With a 3 node cluster and RF 3 isn't it a problem if one node fails
(due to hardware problems, for example). According to the C* docs, writes fail
if the number of nodes is smaller than the RF.
I agree that it will run fine as long as all nodes are up and
I do not agree with this advice. It can be perfectly reasonable to have
#nodes < 2*RF.
It is common to deploy a 3 node cluster with RF=3 and it works fine as long
as each node can handle 100% of your data, and keep up with the workload.
-Tupshin
On Apr 14, 2014 5:25 AM, "Markus Jais" wrote:
>
Hi Markus,
> "It is generally not recommended to set a replication factor of 3 if
> you have fewer than six nodes in a data center".
Actually you can create a cluster with 3 nodes and replication level 3.
But in this case if one of them would fail cluster become inconsistent.
In this way minimum re
Hello,
currently reading the "Practical Cassandra". In the section about replication
factors the book says:
"It is generally not recommended to set a replication factor of 3 if you have
fewer than six nodes in a data center".
Why is that? What problems would arise if I had a replication factor
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