Log Replication Threshold for Full Reseed in Exchange Server 2019

Krismayanto 0

How many log files failing to replicate between the active and passive copies of an Exchange Server 2019 database will trigger a full reseed?

Bruce Jing-MSFT 9,290 Reputation points Microsoft Vendor

2025-02-12T09:18:29.3133333+00:00

Hello, @Krismayanto

It's been a long time since I've heard from you, have you solved your problem yet? Did my previous reply help you？ If it was useful, you can mark it as an answer. Thank you for your understanding and support.
Krismayanto 0 Reputation points

2025-02-12T14:12:23.8866667+00:00

Hi Jing, I believe the 3x 15 minutes applies if we enable Auto reseed, which is a new feature. My Exchange DBs without Auto reseed feature can still resume replication even after being suspended for a few hours, for example due to Network issue between sites.

1 answer

Bruce Jing-MSFT 9,290 Reputation points Microsoft Vendor

2025-02-10T08:05:19.58+00:00

Hi,@Krismayanto

Thanks for posting your question in the Microsoft Q&A forum.

Triggering AutoReseed is not determined by the number of replication log file failures, but by the fact that the database replica has been in the FailedandSuspended state for 15 consecutive minutes.

You can refer to this official document for details:https://learn.microsoft.com/en-us/exchange/high-availability/database-availability-groups/autoreseed?view=exchserver-2019&source=recommendations

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Amit Singh 5,071 Reputation points

2025-02-12T07:13:36.89+00:00

Agree with Bruce points, if database is in a FailedAndSuspended state. That said, if logs aren’t replicating properly, you can check with following command:

Get-MailboxDatabaseCopyStatus *

If AutoReseed isn’t working as expected, you can manually reseed the Exchange database.

Please Note: Since the web sites are not hosted by Microsoft, the links may change without notice. Microsoft does not guarantee the accuracy of this information.

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Krismayanto 0 Reputation points

2025-02-12T14:14:22.0533333+00:00

Hi Jing, I believe the 3x 15-minute rule applies if we enable AutoReseed, which is a new feature. My Exchange databases can still resume replication even after being suspended for a few hours, for example, due to a network issue between sites

Krismayanto 0 Reputation points

2025-02-12T14:19:31.2933333+00:00

Hi Amit, the problem is not about the state, or how to check the status. Sometimes the replication suspended for a few hours (more than 3x 15 mins) because of network issue between sites. Sometimes it can resume, but sometimes we need to Update/Full reseed the DB. Question is what condition will requires full reseed.

Bruce Jing-MSFT 9,290 Reputation points Microsoft Vendor

2025-02-13T09:49:04.3366667+00:00

hi，@Krismayanto

Some common scenarios that require a full reseed include: • Corruption or loss of the passive database copy – If the database file on a passive server becomes corrupted, deleted, or otherwise unusable, incremental log replay isn’t possible and a full reseed is needed.

• Log chain breakage – When there’s a break in the log chain (for example, if the necessary log files have been deleted, truncated, or are missing due to disk issues or configuration errors), the passive copy cannot catch up incrementally. A full reseed is required to re-establish the correct sequence.

• Extended downtime – If a passive copy has been offline for an extended period, the log files required to bring it up to date might no longer be available. In that case, you must perform a full reseed from the active copy.

• Configuration changes – In some cases, such as after certain upgrades or significant changes to the database, the passive copy might not be compatible with the active copy’s state. Though less common, this might also lead to a full reseed requirement.

In summary, any situation where the passive mailbox database copy can’t apply the incremental log changes due to data corruption, missing logs, or an incompatible state will require a full reseed to ensure the copy is valid and synchronized with the active database.

Bruce Jing-MSFT 9,290 Reputation points Microsoft Vendor

2025-02-25T07:54:49.24+00:00

Hello, @

Krismayanto

It's been a long time since I've heard from you, have you solved your problem yet? Did my previous reply help you？ If it was useful, you can mark it as an answer. Thank you for your understanding and support.
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Log Replication Threshold for Full Reseed in Exchange Server 2019

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