<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Jan 20, 2017 at 7:37 AM, Tatsuo Ishii <span dir="ltr"><<a href="mailto:ishii@sraoss.co.jp" target="_blank">ishii@sraoss.co.jp</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><span class="gmail-">> On Mon, Jan 16, 2017 at 12:10 PM, Tatsuo Ishii <<a href="mailto:ishii@sraoss.co.jp">ishii@sraoss.co.jp</a>> wrote:<br>
><br>
>> Hi Usama,<br>
>><br>
>> If my understanding is correct, by using the quorum, Pgpool-B and<br>
>> <span id="gmail-b79a4628-f5b9-4b1d-8852-74dbcefc35f6" class="gmail-GINGER_SOFTWARE_mark">Pgpool</span>-C decides that B1 is healthy. What happens when Pgpool-A tries<br>
>> <span id="e52190cf-f134-4600-8428-f400aead5078" class="gmail-GINGER_SOFTWARE_mark gmail-GINGER_SOFTWARE_mark">to</span> connect to B1 if the network failure between Pgpool-A and B1<br>
>> <span id="gmail-f1c4918c-6a37-42de-ae3d-4a10b254ff1d" class="gmail-GINGER_SOFTWARE_mark">continues</span>? I guess clients connect to Pgpool-A get <span id="gmail-a5d9b1c2-d4af-402b-9ced-7cf97ceaa6b5" class="gmail-GINGER_SOFTWARE_mark">error</span> and failed to<br>
>> <span id="gmail-92960285-b464-4178-bc9d-bdc5eba072e8" class="gmail-GINGER_SOFTWARE_mark">connect</span> to database?<br>
>><br>
><br>
> Yes, that is correct. I think what we can do in this scenario is, If the<br>
> <span id="gmail-64fa7d7b-7423-4b0b-a771-a6da07b93d07" class="gmail-GINGER_SOFTWARE_mark">Pgpool</span>-A is not allowed to failover B1 because other nodes in the cluster<br>
> (<span id="gmail-64770c14-ed72-4dc3-95a9-64d676409cb2" class="gmail-GINGER_SOFTWARE_mark">Pgpool</span>-B and Pgpool-C) does not agree with the failure of B1 then the<br>
> <span id="gmail-82824740-ada4-4cce-a4c6-f100c1c570e0" class="gmail-GINGER_SOFTWARE_mark">Pgpool</span>-A will throw an error to its clients if B1 was the master/primary<br>
> <span id="gmail-0a5123e1-a6b4-4462-b7e5-23f8461d13c0" class="gmail-GINGER_SOFTWARE_mark">Backend</span> Server. Otherwise, if B1 was the Standby server then Pgpool-A would<br>
> <span id="gmail-f80c6c1f-2dfe-487d-907f-6b1abc70de26" class="gmail-GINGER_SOFTWARE_mark">continue</span> serving the clients without using the unreachable PostgreSQL<br>
> <span id="gmail-adf950a7-5641-4acd-a54e-3b82a5ed8c38" class="gmail-GINGER_SOFTWARE_mark">server</span> B1.<br>
<br>
</span>Well, that sounds overly complex to me. In this case it is likely that<br>
<span id="gmail-bd7fa43c-f9ec-47b7-aff5-dbb1b1ad59c1" class="gmail-GINGER_SOFTWARE_mark">network</span> devices or switch ports used by Pgpool-A are broken. In this<br>
<span id="gmail-4d2ea7a6-fd75-41e0-a3f7-7b3bcb822160" class="gmail-GINGER_SOFTWARE_mark">situation</span>, as a member of watchdog clusters, Pgpool-A cannot be<br>
<span id="gmail-454bb606-f9d8-4a3d-a51b-6f832560afb0" class="gmail-GINGER_SOFTWARE_mark">trusted</span> any more thus we can let Pgpool-II retire from the watchdog<br>
<span id="gmail-6b7851df-6bf0-4325-985f-ab4fe7889fa9" class="gmail-GINGER_SOFTWARE_mark">cluster</span>.<br></blockquote><div><br></div><div>Basically the scenario mentioned in the initial proposal is the very simplistic, which has all Pgpool-II and Database servers located inside a single network and as you pointed out the failure scenario would be more likely because of a network device failure.<br></div><div><br></div><div>But if we consider a situation where the Pgpool-II servers and PostgreSQL servers are distributed in multiple or even just two availability zones then the network partitioning can happen because of disruption of the link connecting the networks in the different availability zone.</div><div><br></div><div>There is also a question ("<a href="http://www.sraoss.jp/pipermail/pgpool-general/2016-December/005237.html">[pgpool-general: 5179] Architecture Questions</a>") posted by a user in <span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-74260722-b80c-4e75-89e8-75eae46196b8" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span 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id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-836164ee-c522-4cea-bfd0-c7ceb63a75ac" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-a86c4082-7bbc-4158-b1ba-ccec6ef5d7d2" class="gmail-GINGER_SOFTWARE_mark">pgpool</span></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark">-general</span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span><span id="gmail-4fca561b-e5eb-48d9-a49d-ca617f5e1cf0" class="gmail-GINGER_SOFTWARE_mark"></span> mailing list who wants a similar type of network that spans over two AWS availability zones and <span id="gmail-900aa638-4f4d-4631-88e2-4143e76fdaef" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-431a9382-4ef3-4aad-adb2-2b5d7acc258f" class="gmail-GINGER_SOFTWARE_mark"><span class="gmail-GINGER_SOFTWARE_mark">Pgpool-II</span></span></span> has no good answer to avoid <span id="gmail-f7ab5286-ac01-49ca-92a9-625eba8446ef" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-0d867b73-1060-473f-afd6-9e7e7160edc2" class="gmail-GINGER_SOFTWARE_mark">split</span></span>-brain of <span id="gmail-f86eab2a-4769-49e2-845c-ceba3eb70640" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-4d09e078-5c94-4ce9-acf1-729af4914878" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-b357732d-50fd-47bf-b6ff-ca2884827a27" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-16157da3-3892-4793-87d0-8263ff623e35" class="gmail-GINGER_SOFTWARE_mark">backend</span></span></span></span> nodes if the corporate link between two zones suffers a glitch.</div><div><br></div><div>Thanks</div><div>Best regards</div><div>Muhammad Usama</div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
Best regards,<br>
<div class="gmail-HOEnZb"><div class="gmail-h5">--<br>
Tatsuo Ishii<br>
SRA OSS, Inc. Japan<br>
English: <a href="http://www.sraoss.co.jp/index_en.php" rel="noreferrer" target="_blank">http://www.sraoss.co.jp/index_<wbr>en.php</a><br>
Japanese:<a href="http://www.sraoss.co.jp" rel="noreferrer" target="_blank">http://www.sraoss.co.<wbr>jp</a><br>
<br>
>> > Hi Hackers,<br>
>> ><br>
>> > This is the proposal to make the failover of <span id="gmail-32f8b794-1b74-4269-8b26-665a76a021e7" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-32f8b794-1b74-4269-8b26-665a76a021e7" class="gmail-GINGER_SOFTWARE_mark">backend</span></span> PostgreSQL nodes<br>
>> > <span id="gmail-b3100076-01d2-4cc4-aa45-12a1282f5363" class="gmail-GINGER_SOFTWARE_mark">quorum</span> aware to make it more robust and fault tolerant.<br>
>> ><br>
>> > Currently Pgpool-II proceeds to <span id="e7ad4e98-9370-41fc-9c7a-ad11acf8433b" class="gmail-GINGER_SOFTWARE_mark gmail-GINGER_SOFTWARE_mark">failover</span> the <span id="gmail-0f7bc414-b381-48f1-9f87-b679d6fff14a" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-0f7bc414-b381-48f1-9f87-b679d6fff14a" class="gmail-GINGER_SOFTWARE_mark">backend</span></span> node as soon as the<br>
>> > <span id="gmail-48fdeffb-d194-41e2-a597-9025a09e4462" class="gmail-GINGER_SOFTWARE_mark">health</span> check detects the failure or in case of an error occurred <span id="gmail-0169f774-882e-40ce-8baf-5689d38d1f14" class="gmail-GINGER_SOFTWARE_mark">on</span> the<br>
>> > <span id="gmail-56624171-9ffd-4500-bd8f-8da23108950f" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-56624171-9ffd-4500-bd8f-8da23108950f" class="gmail-GINGER_SOFTWARE_mark">backend</span></span> connection (when fail_over_on_backend_error is set). This is good<br>
>> > <span id="gmail-02a385fe-7209-4ec1-be20-d09460b3c1bd" class="gmail-GINGER_SOFTWARE_mark">enough</span> for the standalone Pgpool-II server.<br>
>> ><br>
>> > But consider the scenario where we have more than one Pgpool-II (Say<br>
>> > <span id="gmail-ac6574de-841c-495d-8495-64ac63201189" class="gmail-GINGER_SOFTWARE_mark">Pgpool</span>-A, Pgpool-B and Pgpool-C) in the cluster connected through<br>
>> <span id="gmail-082e52c6-1d74-4aec-bccd-b59a349f003b" class="gmail-GINGER_SOFTWARE_mark">watchdog</span><br>
>> > <span id="gmail-9a0df5da-7441-46da-b3d1-5fc0404a8051" class="gmail-GINGER_SOFTWARE_mark">and</span> each Pgpool-II node is configured with two PostgreSQL <span id="efa69def-87bc-49af-8aad-1493875e9ec6" class="gmail-GINGER_SOFTWARE_mark gmail-GINGER_SOFTWARE_mark">backends</span> (B1<br>
>> <span id="gmail-d9293f51-dbd0-42df-9fa4-459f0e98798a" class="gmail-GINGER_SOFTWARE_mark">and</span><br>
>> > B2).<br>
>> ><br>
>> > Now if due to some network glitch or an issue, Pgpool-A fails or loses<br>
>> <span id="gmail-a198f746-79a3-4d9d-9e14-832499dd7026" class="gmail-GINGER_SOFTWARE_mark">its</span><br>
>> > <span id="gmail-80af5c7e-876d-4fdb-9d94-6195d6f05510" class="gmail-GINGER_SOFTWARE_mark">network</span> connection with <span id="gmail-86f66a45-b7fe-45b5-9b86-20821a7f4e65" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-986e8e6a-a7ee-4dba-aba4-c5071a628ade" class="gmail-GINGER_SOFTWARE_mark">backend</span></span> B1, The Pgpool-A will detect the failure<br>
>> > <span id="gmail-9daa7dc8-f8f0-4804-966a-7dd4d0fd5ceb" class="gmail-GINGER_SOFTWARE_mark">and</span> detach (failover) the B1 <span id="gmail-d278b544-f751-4f4f-8767-d136851cc46a" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-bad28dd1-7937-4c8a-b575-e59a4db83b3c" class="gmail-GINGER_SOFTWARE_mark">backend</span></span> and also pass this information to<br>
>> <span id="gmail-47eb2892-8b1f-4c83-993c-1d5f0a701738" class="gmail-GINGER_SOFTWARE_mark">the</span><br>
>> > <span id="gmail-50217a7a-3ab3-4f69-9ad4-58a8f422e4b2" class="gmail-GINGER_SOFTWARE_mark">other</span> Pgpool-II nodes (Pgpool-II B and Pgpool-II C), Although the Backend<br>
>> > B1 was perfectly healthy and it was also reachable from Pgpool-B and<br>
>> > <span id="gmail-44f4b843-3548-44cb-900d-c66e79c5e186" class="gmail-GINGER_SOFTWARE_mark">Pgpool</span>-C nodes, But still because of a network glitch between Pgpool-A<br>
>> <span id="gmail-28285afb-8945-479c-b632-6d533e14cecc" class="gmail-GINGER_SOFTWARE_mark">and</span><br>
>> > <span id="gmail-6b832b68-eadf-4641-a6f2-857390c4c09b" class="gmail-GINGER_SOFTWARE_mark">Backend</span> B1, it will get detached from the cluster and the worst part is,<br>
>> <span id="gmail-c1abd5e4-d765-485a-9460-5aedf1103e83" class="gmail-GINGER_SOFTWARE_mark">if</span><br>
>> > <span id="gmail-0a853656-022c-43bd-950a-ab5455ec34e1" class="gmail-GINGER_SOFTWARE_mark">the</span> B1 was a master PostgreSQL (in master-standby configuration), the<br>
>> > Pgpool-II <span id="gmail-9e46ccb6-5407-4622-bb52-22d8200f677c" class="gmail-GINGER_SOFTWARE_mark">failover</span> would also promote the B2 PostgreSQL node as a new<br>
>> > <span id="gmail-f31c87c4-5584-4f05-8786-4ce989428b03" class="gmail-GINGER_SOFTWARE_mark">master</span>, <span id="gmail-5d057625-bd5d-4043-94e9-53bcb7567948" class="gmail-GINGER_SOFTWARE_mark">hense</span> making the way <span id="gmail-b82f78ba-e6a9-41ea-bfa2-26ff84f37ce8" class="gmail-GINGER_SOFTWARE_mark">for</span> split-brain and/or data corruptions.<br>
>> ><br>
>> > So my proposal is that when the Watchdog is configured in Pgpool-II the<br>
>> > <span id="gmail-58d81b8b-be41-46e0-8270-078f9a170ea2" class="gmail-GINGER_SOFTWARE_mark"><span id="gmail-58d81b8b-be41-46e0-8270-078f9a170ea2" class="gmail-GINGER_SOFTWARE_mark">backend</span></span> health check of Pgpool-II should consult with other attached<br>
>> > Pgpool-II nodes over the watchdog to decide if the Backend node is<br>
>> <span id="gmail-45417e7d-10aa-48a5-8f5a-494ad983d7e6" class="gmail-GINGER_SOFTWARE_mark">actually</span><br>
>> > <span id="gmail-8109725e-06cd-4e77-afd0-a7376e9fcdce" class="gmail-GINGER_SOFTWARE_mark">failed</span> or if it is just a localized glitch/false alarm. And the failover<br>
>> <span id="gmail-cf859e8c-2051-4f8d-9b26-0faacddd66a2" class="gmail-GINGER_SOFTWARE_mark">on</span><br>
>> > <span id="gmail-7f2f9bc5-ec40-45f8-b4dc-e2e4d498bc70" class="gmail-GINGER_SOFTWARE_mark">the</span> node should only be performed, when the majority of cluster members<br>
>> > <span id="gmail-d77e8a78-527c-42d3-a426-9b6ebe0d7393" class="gmail-GINGER_SOFTWARE_mark">agrees</span> on the failure of nodes.<br>
>> ><br>
>> > This quorum aware architecture of failover will prevents the <span id="gmail-94a0366c-0226-4904-af4d-4200ac4a6dc1" class="gmail-GINGER_SOFTWARE_mark">false</span><br>
>> > <span id="gmail-8a0ca242-ee10-4194-8310-83dbd6382bad" class="gmail-GINGER_SOFTWARE_mark">failovers</span> and split-brain scenarios in the Backend nodes.<br>
>> ><br>
>> > What are your thoughts and suggestions on this?<br>
>> ><br>
>> > Thanks<br>
>> > Best regards<br>
>> > Muhammad Usama<br>
>><br>
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