Availability Groups and dm_hadr_database_replica_states dmv

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Availability Groups and dm_hadr_database_replica_states dmv

ganci.mark

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April 30, 2018 at 1:07 pm

#328601

Hello.
I am trying to figure out what the difference is between the following columns on
sys.dm_hadr_database_replica_states (SQL 2016 )
last_sent_time
Last_receive_time
last_hardened_time
Last_redo_time
last_sent_time and last_receive_time seem to age out while last_hardened_time and last_redo_time seem to stay in line with changes being made on the primary and replication.
What do the values in last_sent_time and last_received_time actually mean/represent?
Thanks
Mark G.

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Michael L John One Orange Chip Points: 27055 More actions · Answer 1

ganci.mark - Monday, April 30, 2018 1:07 PM
Hello.
I am trying to figure out what the difference is between the following columns on
sys.dm_hadr_database_replica_states (SQL 2016 )
last_sent_time
Last_receive_time
last_hardened_time
Last_redo_time
last_sent_time and last_receive_time seem to age out while last_hardened_time and last_redo_time seem to stay in line with changes being made on the primary and replication.
What do the values in last_sent_time and last_received_time actually mean/represent?
Thanks
Mark G.

Well, typing sys.dm_hadr_database_replica_states into a google search returned this link:
https://docs.microsoft.com/en-us/sql/relational-databases/system-dynamic-management-views/sys-dm-hadr-database-replica-states-transact-sql?view=sql-server-2017

Which states:

last_sent_time

datetime

Time when the last log block was sent.

last_received_time

datetime

Time when the log block ID in last message received was read on the secondary replica.

Michael L John
If you assassinate a DBA, would you pull a trigger?
To properly post on a forum:
http://www.sqlservercentral.com/articles/61537/

ganci.mark Hall of Fame Points: 3533 More actions · Answer 2

Thanks Mike.
I did get that far with the Microsoft documentation however What I was looking for was a better explanation of what each value meant in relation to the replication process.
last_sent_time
Last_receive_time
last_hardened_time
Last_redo_time
How are these related to each other and the data replication process.

Real example:
last_sent_time =2018-05-01 16:29:46.050
last_received_time = 2018-05-01 16:29:46.050
last_redone_time = 2018-05-01 16:29:36.563
last_hardened_time= 2018-05-01 16:29:38.040
Does this mean the changes were sent/received at 16:29:46 and it took 10 seconds to "redo"(apply) them and 2 seconds to "commit"(harden) them?

Thanks

Mark G.