IDS Forum

Re: HDR- Distance and Latency

Posted By: MARK JALKIEWICZ
Date: Wednesday, 19 July 2017, at 11:17 a.m.

In Response To: HDR- Distance and Latency (MURALI PAZHAYANNUR)

here's my story ... IDS 11.50.FC8.

Dallas TX to Wilmington DE (> 1000 miles). At the busiest times (over 40 commits per second) the primary would block waiting on the log latch. R&D has corrected that issue in later versions I believe , not totally sure on since we moved to using ER instead on 11.70.FC7 . So yes.. latency does come into play and you have to also consider your internet business provider and the level of service they provide. Network congestion will torpedo your HDR primary, no doubt about it. RSS was not an option due to the SLA agreements in place but if you can live with the async that RSS comes with then consider that as an option. After switching to ER, we do get occasional ER spooling due to network latency/spooling but at least the "primary" does not block ,most important.

You can tune HDR on the secondary by minimizing the checkpoint duration's (they block the primary to ensure data consistency) , see LRU MAX & MIN tuning and setting DRINTERVAL accordingly.

Finally there is this with HDR: If your network is not very reliable (in other works just like any other network) occasionally the secondary will detect that the primary is not online and not re-establish connectivity automatically due to the SMX thread exiting which in that case a restart of the secondary is needed to get them talking again. But there will be times where that will not work and you have to restart the engine on the primary to re-establish connectivity. I opened several PMRs over this and nothing ever became of it, its a definite pain point.

IMO HDR is a viable solution if the servers are relatively close together but if they are not (such as 1000+ miles apart) and if the primary is highly OLTP then start kicking the tires on ER or RSS.

Mark

Messages In This Thread

• HDR- Distance and Latency
  MURALI PAZHAYANNUR -- Wednesday, 19 July 2017, at 9:40 a.m.
  • Re: HDR- Distance and Latency
    Art Kagel -- Wednesday, 19 July 2017, at 10:20 a.m.
    • Re: HDR- Distance and Latency
      Madison Pruet -- Wednesday, 19 July 2017, at 1:46 p.m.
  • Re: HDR- Distance and Latency
    MARK JALKIEWICZ -- Wednesday, 19 July 2017, at 11:17 a.m.

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