Hi Renaud, Thank you so much for your response. It is very helpful and it helped me understand the need for turning on buffering.
Is it recommended to keep the buffering enabled all the time on the source cluster? If the target cluster is up and running and the cdcr is started, can i turn off the buffering on the source site? As you have mentioned, the transaction logs are kept on the source cluster, until the data is replicated on the target cluster, once the cdcr is started, is there a possibility that if on the target cluster On Tue, Jun 14, 2016 at 6:50 AM, Davis, Daniel (NIH/NLM) [C] < daniel.da...@nih.gov> wrote: > I must chime in to clarify something - in case 2, would the source cluster > eventually start a log reader on its own? That is, would the CDCR heal > over time, or would manual action be required? > > -----Original Message----- > From: Renaud Delbru [mailto:renaud@siren.solutions] > Sent: Tuesday, June 14, 2016 4:51 AM > To: solr-user@lucene.apache.org > Subject: Re: Regarding CDCR SOLR 6 > > Hi Bharath, > > The buffer is useful when you need to buffer updates on the source cluster > before starting cdcr, if the source cluster might receive updates in the > meanwhile and you want to be sure to not miss them. > > To understand this better, you need to understand how cdcr clean > transaction logs. Cdcr when started (with the START action) will > instantiate a log reader for each target cluster. The position of the log > reader will indicate cdcr which transaction logs it can clean. If all the > log readers are beyond a certain point, then cdcr can clean all the > transaction logs up to this point. > > However, there might be cases when the source cluster will be up without > any log readers instantiated: > 1) The source cluster is started, but cdcr is not started yet > 2) the source cluster is started, cdcr is started, but the target cluster > was not accessible when cdcr was started. In this case, cdcr will not be > able to instantiate a log reader for this cluster. > > In these two scenarios, if updates are received by the source cluster, > then they might be cleaned out from the transaction log as per the normal > update log cleaning procedure. > That is where the buffer becomes useful. When you know that while starting > up your clusters and cdcr, you will be in one of these two scenarios, then > you can activate the buffer to be sure to not miss updates. Then when the > source and target clusters are properly up and cdcr replication is properly > started, you can turn off this buffer. > > -- > Renaud Delbru > > On 14/06/16 06:41, Bharath Kumar wrote: > > Hi, > > > > I have setup cross data center replication using solr 6, i want to > > know why the buffer needs to be enabled on the source cluster? Even if > > the buffer is not enabled, i am able to replicate the data between > > source and target sites. What is the advantages of enabling the buffer > > on the source site? If i enable the buffer, the transaction logs are > > never deleted and over a period of time we are running out of disk. > > Can you please let me know why the buffer enabling is required? > > > > -- Thanks & Regards, Bharath MV Kumar "Life is short, enjoy every moment of it"
