[pgpool-general: 9110] Re: Postgres/pgpool HA failover process

[Mukesh Tanuku]

BTW here is the network configuration we set as

UTOCONNECT_PRIORITY=120
BOOTPROTO=dhcp
DEVICE=eth0
DHCPV6C=yes
HWADDR=<MAC Address>
IPV6INIT=yes
ONBOOT=yes
TYPE=Ethernet
USERCTL=no

Regards
Mukesh Tanuku

On Wed, May 29, 2024 at 12:53 PM Mukesh Tanuku <mukesh.postgres at gmail.com>
wrote:

> Thanks Bo for your response to my email.
>
> Below is the parameters:
>
>
>
> * if_up_cmd = '/usr/bin/sudo /sbin/ip addr add $_IP_$/24 dev enp0s8 label
> enp0s8:0'  if_down_cmd = '/usr/bin/sudo /sbin/ip addr del $_IP_$/24 dev
> enp0s8'  arping_cmd = '/usr/bin/sudo /usr/sbin/arping -U $_IP_$ -w 1 -I
> enp0s8'*
>
> The above commands are working on Leader node. and once the VIP is up
> successfully then we can run the pcp commands via VIP host work only from
> the leader node locally. if we try to execute the PCP comands via VIP
> throws an error
> ERROR: connection to host "<VIP>" failed with error "No route to host"
>
> What's the possible cause in this case?
>
> Regards
> Mukesh Tanuku
>
>
> On Tue, May 28, 2024 at 5:30 AM Bo Peng <pengbo at sraoss.co.jp> wrote:
>
>> Hi,
>>
>> > Hello Everyone,
>> >
>> > We are working on to setup a High available solution for postgres and
>> > running some test cases
>> > based on that we need some clarification on the HA setup as per the same
>> > configuration given in this example
>> > <https://www.pgpool.net/docs/42/en/html/example-cluster.html>
>>
>> If you want to configure a new cluster,
>> we recommend using the latest version.
>>
>> https://www.pgpool.net/docs/latest/en/html/example-cluster.html
>>
>> > Question - 01
>> > Regarding the active client connections that are connecting via delegate
>> > VIP, what happens to those connections during the failover process? If
>> > either the primary DB goes down (gracefully/crash) then the
>> > active connection will get hung till the new primary DB is available or
>> > those active connections get terminated?
>>
>> The existing connections will be disconnected if primary DB is down.
>> However, the subsequent connections will be routed to the new primary.
>>
>> > What if the same case for Leader pgpool service as well?
>>
>> Yes.
>>
>> > Questions - 02
>> > Configuring the delegate IP:
>> > a. Are there any standards/limitations for choosing the unused IP as
>> > delegate IP? I mean like the IP must be within the same subnet range of
>> all
>> > the nodes in the cluster?
>>
>> No limitations in Pgpool-II, it depends on the OS.
>> Pgpool-II using "ip addr ..." command to assign or release a delegate IP.
>>
>> Below is the parameters:
>>
>>   if_up_cmd = '/usr/bin/sudo /sbin/ip addr add $_IP_$/24 dev enp0s8 label
>> enp0s8:0'
>>   if_down_cmd = '/usr/bin/sudo /sbin/ip addr del $_IP_$/24 dev enp0s8'
>>   arping_cmd = '/usr/bin/sudo /usr/sbin/arping -U $_IP_$ -w 1 -I enp0s8'
>>
>> You need to make sure the commands work.
>>
>> > b. Any challenges we see for non-root user to work with VIP? because we
>> run
>> > the pgpool with non-root user.
>>
>> You need to make sure the non-root user can execute ip and arping command
>> with sudo
>> without a password.
>>
>> --
>> Bo Peng <pengbo at sraoss.co.jp>
>> SRA OSS LLC
>> TEL: 03-5979-2701 FAX: 03-5979-2702
>> URL: https://www.sraoss.co.jp/
>>
>
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