Re: Does nodetool repair stop the node to answer requests ?
For the cases where repair brings down a cluster, I can safely say that cluster has more problems than just repair. Consider the load caused by repair to be somewhat equivalent to losing a node. This is not a 1 for 1 comparison, as the node you're running repair on is up albeit busy,and the potential streaming impacts can be of course worse, however, the entire design of Cassandra is around being able to tolerate 1 or more node outages (depending on your level of sizing) and not have your application be affected. On Thu, Jan 22, 2015 at 1:15 PM, SEGALIS Morgan msega...@gmail.com wrote: Don't think it is near failure, it uses only 3% of the CPU and 40% of the RAM if that is what you meant. 2015-01-22 19:58 GMT+01:00 Robert Coli rc...@eventbrite.com: On Thu, Jan 22, 2015 at 10:53 AM, SEGALIS Morgan msega...@gmail.com wrote: what do you mean by operating correctly ? I mean that if you are operating near failure, repair might trip a node into failure. But if you are operating correctly, repair should not. =Rob -- Morgan SEGALIS -- Thanks, Ryan Svihla
Re: Does nodetool repair stop the node to answer requests ?
what do you mean by operating correctly ? I only use dynamic columns if that helps... 2015-01-22 19:10 GMT+01:00 Robert Coli rc...@eventbrite.com: On Thu, Jan 22, 2015 at 9:36 AM, SEGALIS Morgan msega...@gmail.com wrote: So I wondered, does a nodetool repair make the server stop serving requests, or does it just use a lot of ressources but still serves request ? In pathological cases, repair can cause a node to seriously degrade. If you are operating correctly, it just uses lots of resources but still serves requests. =Rob http://twitter.com/rcolidba -- Morgan SEGALIS
Re: Does nodetool repair stop the node to answer requests ?
If I change the network topology, I have to run repair right before adding a new cluster ? I know that I should put 2 more nodes, so far, I'm preparing myself to create a new node on a new DC, but on same network (ping really low), so at least I would have a backup server if anything happens, just need to wrap my head around the network topology and understand what I do before starting a new node. 2015-01-22 19:15 GMT+01:00 Flavien Charlon flavien.char...@gmail.com: I don't think you can do nodetool repair on a single node cluster. Still, one day or another you'll have to reboot your server, at which point your cluster will be down. If you want high availability, you should use a 3 nodes cluster with RF = 3. On 22 January 2015 at 18:10, Robert Coli rc...@eventbrite.com wrote: On Thu, Jan 22, 2015 at 9:36 AM, SEGALIS Morgan msega...@gmail.com wrote: So I wondered, does a nodetool repair make the server stop serving requests, or does it just use a lot of ressources but still serves request ? In pathological cases, repair can cause a node to seriously degrade. If you are operating correctly, it just uses lots of resources but still serves requests. =Rob http://twitter.com/rcolidba -- Morgan SEGALIS
Re: Does nodetool repair stop the node to answer requests ?
On Thu, Jan 22, 2015 at 10:22 AM, Jan cne...@yahoo.com wrote: Running a 'nodetool repair' will 'not' bring the node down. It's not something that happens during normal operation. If something goes sideways, and the resource usage climbs, a repair can definitely cripple a node. Your question: does a nodetool repair make the server stop serving requests, or does it just use a lot of ressources but still serves request Answer: NO, the server will not stop serving requests. It will use some resources but not enough to affect the server serving requests. I don't think this is right. I've personally seen repair operations cause real bad things to happen to an entire Cassandra cluster. The only mitigation was to shut that misbehaving node down and then normal operations continued within the cluster. hope this helps Jan Cheers! -Tim
Re: Does nodetool repair stop the node to answer requests ?
Thanks, this is a straight forward answer, exactly what I needed ! 2015-01-22 19:22 GMT+01:00 Jan cne...@yahoo.com: Running a 'nodetool repair' will 'not' bring the node down. Your question: does a nodetool repair make the server stop serving requests, or does it just use a lot of ressources but still serves request Answer: NO, the server will not stop serving requests. It will use some resources but not enough to affect the server serving requests. hope this helps Jan -- Morgan SEGALIS
Re: Does nodetool repair stop the node to answer requests ?
On Thu, Jan 22, 2015 at 10:53 AM, SEGALIS Morgan msega...@gmail.com wrote: what do you mean by operating correctly ? I mean that if you are operating near failure, repair might trip a node into failure. But if you are operating correctly, repair should not. =Rob
Re: Does nodetool repair stop the node to answer requests ?
Don't think it is near failure, it uses only 3% of the CPU and 40% of the RAM if that is what you meant. 2015-01-22 19:58 GMT+01:00 Robert Coli rc...@eventbrite.com: On Thu, Jan 22, 2015 at 10:53 AM, SEGALIS Morgan msega...@gmail.com wrote: what do you mean by operating correctly ? I mean that if you are operating near failure, repair might trip a node into failure. But if you are operating correctly, repair should not. =Rob -- Morgan SEGALIS
Re: Does nodetool repair stop the node to answer requests ?
On Thu, Jan 22, 2015 at 9:36 AM, SEGALIS Morgan msega...@gmail.com wrote: So I wondered, does a nodetool repair make the server stop serving requests, or does it just use a lot of ressources but still serves request ? In pathological cases, repair can cause a node to seriously degrade. If you are operating correctly, it just uses lots of resources but still serves requests. =Rob http://twitter.com/rcolidba
Re: Does nodetool repair stop the node to answer requests ?
I don't think you can do nodetool repair on a single node cluster. Still, one day or another you'll have to reboot your server, at which point your cluster will be down. If you want high availability, you should use a 3 nodes cluster with RF = 3. On 22 January 2015 at 18:10, Robert Coli rc...@eventbrite.com wrote: On Thu, Jan 22, 2015 at 9:36 AM, SEGALIS Morgan msega...@gmail.com wrote: So I wondered, does a nodetool repair make the server stop serving requests, or does it just use a lot of ressources but still serves request ? In pathological cases, repair can cause a node to seriously degrade. If you are operating correctly, it just uses lots of resources but still serves requests. =Rob http://twitter.com/rcolidba
Re: Does nodetool repair stop the node to answer requests ?
Running a 'nodetool repair' will 'not' bring the node down. Your question: does a nodetool repair make the server stop serving requests, or does it just use a lot of ressources but still serves request Answer: NO, the server will not stop serving requests. It will use some resources but not enough to affect the server serving requests. hope this helpsJan
