If this is Auto Seeding then you should not use that method with a database in the Terabytes. It is not a great way for that size of database. You should use Backup/Restore. Also ensure that you have the server certificate restored in the replicas master database.
Performance Issue: Extremely Long Time to Add Large TDE-Encrypted Database to Cross-Site Availability Group
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Mona Seddik
0
Reputation points
We are experiencing significant delays when adding large databases (4TB+) encrypted with Transparent Data Encryption (TDE) to an Availability Group replica servers using scripts. This operation takes an unacceptably long time is this an expected behavior? We are seeking guidance on the recommended workaround or best practices to mitigate this issue and
SQL Server Database Engine
{count} votes
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Ben Miller-(DBADuck) 275 Reputation points MVP2025-09-21T14:17:20.85+00:00 How are you trying to add the database to the AG?
Auto seeding? Backup/Restore?
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Nithin Krishna Madadi 0 Reputation points Microsoft External Staff Moderator2025-10-27T09:12:54.0566667+00:00 Hi Mona Seddik,
I wanted to check if you had the opportunity to review the information provided. Please feel free to contact us if you have any further questions.Thank you.
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Nithin Krishna Madadi 0 Reputation points Microsoft External Staff Moderator
2025-10-31T12:05:10.6633333+00:00 Hi Mona Seddik,
May I check if this issue has been resolved? If not, Please feel free to contact us if you have any further questions.
Thank you
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1 answer
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Ben Miller-(DBADuck) 275 Reputation points MVP
2025-09-21T14:19:39.2133333+00:00 -
Mona Seddik 0 Reputation points
2025-09-22T08:00:43.2366667+00:00 I use backup and restore script
I backup db and transaction log in the share folder and restore certificate in the secondary master databases, it's restored and joined the AG successfully but talking long time
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Ben Miller-(DBADuck) 275 Reputation points MVP
2025-09-22T15:12:32.55+00:00 When you say extremely long to add the database, you mean that everything is restored and it takes a long time to have the database fully joined to the AG. You are not speaking about the restore time or other stuff? Just the add to the AG.
What state does it stay in and what mode are you in? Async or Synchronous?
How often do you backup the transaction log? In other words, when you restore the full and transaction log, how long ago was the transaction log and how often do you take log backups?
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Mona Seddik 0 Reputation points
2025-09-23T11:21:42.8366667+00:00 I took almost 3 hours to backup the DB and transaction log, and while restoring it into the secondary node, it takes around a day to restore. I just need to know if the longtime of restore is related to TDE encryption or not?
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Ben Miller-(DBADuck) 275 Reputation points MVP
2025-09-23T15:22:16.68+00:00 Encryption will play into it a little. The most critical piece of timing on the restore is the location relative to 1) Where is the database backup file you are restoring from? Is it in the same location as the database engine you are restoring it to? Is it in the datacenter where the source is? Network traversal is the most impactful time wise. And 2) Is the backup compressed?
Restore could take longer due to encryption if you have a very large log file or a lot of empty space in your database. SQL has to write all bytes in an encrypted database regardless if it is empty or not, because it is not really empty, it is a bunch of 0s for empty space due to encryption.
But to your question about 3 hours to back it up and 1 day to restore. That sounds to me like it is where the database backup is located or it is that you have REALLY slow storage on the cross-site database server. The combination of the 2 are going to be why it takes so long.
Suggestion: Put the backup files in the same location as the database server you are restoring to and then test the restore. It will be much faster. I am guessing that your link between the 2 sites is not super fast.
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