Tuesday, January 20, 2026

Oracle Database Encryption (TDE)

Oracle TDE (Transparent Data Encryption) is a critical piece of data protection, and online encryption is a great tool you can use to simplify the process of encrypting or rekeying your tablespaces. In this post I will go through the process of 
  • Online encrypting an unencrypted tablespace to TDE
  • Restarting encrypting a tablespace within a database that crashed during the process
  • Re-encrypted tablespaces with a stronger encryption key (AES128 --> AES256)
  • What happens to a standby database when I use encryption and when I rekey.

Throughout this blog post I am will be using queries from my previous blog you can find here.

Environment


First my environment. 
  • Primary DB : ORCLCDB - DB 19.28 
  • Standby DB : ORCLSTBY - DB 19.28 
  • Both databases are using OMF to simplify naming files
  •  Encryption - Using Local wallet file
The parameters that affect encryption are using the default values.
Parmeter
Name                           Value                Default?
------------------------------ -------------------- ----------
tablespace_encryption          MANUAL_ENABLE        TRUE
encrypt_new_tablespaces        CLOUD_ONLY           TRUE
Using these parameters, new tablespaces will not be encrypted unless the DDL explicitly mentions encrypting the tablespace.

NOTE: Since I am using 19c, the default encryption Algorithm used will be AES128. Set _tablespace_encryption_default_algorithm to 'AES256' to change the default.

Encrypting my tablespace


Above is the Encryption clause that you can add to "ALTER TABLESPACE" to manage encrypted tablespaces.
For this post, I will concentrate on ONLINE encryption.

New tablespace

I am going to create a new tablespace in my PDB and I want any new tablespaces to be encrypted.
  •  alter system set encrypt_new_tablespaces=always;
  • Create tablespace encrypt_test;
Running my query against the database, I can see that it created a tablespace and by default that tablespace was created as AES128.
PDB Name   Tablespace Name Enc.  Enc. alg   Master Key ID             Key ID                              tablespace Encryt key (trunc)
---------- --------------- ----- ---------- ------------------------- ----------------------------------- ------------------------------
CDB$ROOT   SYSAUX          NO               AZTq/iBVq0/Kv5Es4oNsgQI=  94EAFE2055AB4FCABF912CE2836C8102    603EC31649CDC3684FE68D3DB376F6
           SYSTEM          NO               AZTq/iBVq0/Kv5Es4oNsgQI=  94EAFE2055AB4FCABF912CE2836C8102    603EC31649CDC3684FE68D3DB376F6
           TEMP            NO               AZTq/iBVq0/Kv5Es4oNsgQI=  94EAFE2055AB4FCABF912CE2836C8102    603EC31649CDC3684FE68D3DB376F6
           UNDOTBS1        NO               AZTq/iBVq0/Kv5Es4oNsgQI=  94EAFE2055AB4FCABF912CE2836C8102    603EC31649CDC3684FE68D3DB376F6
           USERS           NO               AQAAAAAAAAAAAAAAAAAAAAA=  00000000000000000000000000000000    000000000000000000000000000000
           ENCRYPT_TEST    YES   AES128     AZTq/iBVq0/Kv5Es4oNsgQI=  94EAFE2055AB4FCABF912CE2836C8102    5635777F4E7A6ACA229FEA10369967

NOTE: I did not change the parameter in my standby database and the tablespace in my standby is also encrypted. The DDL sent to the standby from the primary ensured that the standby also encrypts the tablespace.

Existing tablespaces

Now I am going to take an existing tablespace and encrypt it online. 
Prior to performing this operation (even though it is online), I am going to take a backup of the database.
To make this more realistic I am using a tablespace with 4 datafiles that are all around 10 GB per datafile.

Tablespace Name    FILE_ID File Name                      Size
--------------- ---------- ------------------------------ ----------
ENCTEST                 13 o1_mf_enctest_npz8393s_.dbf     14.454 GB
ENCTEST                 14 o1_mf_enctest_npz8gvz0_.dbf      8.589 GB
ENCTEST                 15 o1_mf_enctest_npz8oy0p_.dbf     10.831 GB
ENCTEST                 16 o1_mf_enctest_npz8yr6p_.dbf     12.793 GB
I am going to encrypt this tablespace on the primary database.

SQL> alter tablespace ENCTEST ENCRYPTION ONLINE ENCRYPT;

My session will not come back until the tablespace is encrypted.

Observations

Alert log and encrypting standby database.

When looking at the alert log for the primary and the standby, I can see the changes occurring.

Primary Database Alert log

ORCLPDB1(3):alter tablespace ENCTEST ENCRYPTION ONLINE ENCRYPT
2026-01-20T10:44:14.923114-07:00
ORCLPDB1(3):About to encrypt tablespace ENCTEST (tsn 3/6)
2026-01-20T10:44:15.020101-07:00
ORCLPDB1(3):TDE converting datafile /home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz8393s_.dbf (13) to /home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_%u_.dbf
2026-01-20T10:48:44.473301-07:00  --> Start Time for Encryption
ORCLPDB1(3):Blocks TDE converted for file /home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqh0w_.dbf size 1894528
2026-01-20T10:48:44.564605-07:00
ORCLPDB1(3):TDE convert operation committed for file /home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqh0w_.dbf
2026-01-20T10:48:46.584235-07:00
ORCLPDB1(3):About to zero out original file "/home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz8393s_.dbf"
2026-01-20T10:50:06.377754-07:00
ORCLPDB1(3):Successfully zero'ed out original file "/home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz8393s_.dbf"
2026-01-20T10:50:06.380150-07:00
ORCLPDB1(3):Successfully deleted original file "/home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz8393s_.dbf"
2026-01-20T10:50:06.388074-07:00

Standby Database Alert log

ORCLPDB1(3):TDE converting datafile /home/db19c/oradata/ORCLSTBY/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz83b9x_.dbf (13) to /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_%u_.dbf
2026-01-20T10:48:44.976604-07:00 ORCLPDB1(3):Blocks TDE converted for file /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqj8h_.dbf size 1894528
2026-01-20T10:48:44.983884-07:00   --> Start Time for Encryption

ORCLPDB1(3):TDE convert operation committed for file /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqj8h_.dbf
2026-01-20T10:48:46.994337-07:00
ORCLPDB1(3):About to zero out original file "/home/db19c/oradata/ORCLSTBY/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz83b9x_.dbf"
2026-01-20T10:50:06.371051-07:00
ORCLPDB1(3):Successfully zero'ed out original file "/home/db19c/oradata/ORCLSTBY/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz83b9x_.dbf"
2026-01-20T10:50:08.012125-07:00
ORCLPDB1(3):Successfully deleted original file "/home/db19c/oradata/ORCLSTBY/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz83b9x_.dbf"
2026-01-20T10:50:08.088219-07:00

Notice that the conversion of the first datafile on the first node started at 
    2026-01-20T10:48:44.473301-07:00
And the standby database started converting the first datafile at
    2026-01-20T10:48:44.976604-07:00
The difference is milliseconds due to latency. 

Observation #1 - With a standby database, the standby database is also immediately encrypting through REDO, and it is encrypting at the same time as the primary.

This was the most interesting item I found when going through the alert log.
After creating a new encrypted copy of a datafile, the process "Zero'ed out" the old datafile prior to deletion.
This was something I had not thought of before.  
When migrating to Encrypted datafiles, this ensures that the original datafile (unencrypted) is overwritten and cannot be "undeleted" and read.
ORCLPDB1(3):About to zero out original file "/home/db19c/oradata/ORCLSTBY/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz83b9x_.dbf"
2026-01-20T10:50:06.371051-07:00
ORCLPDB1(3):Successfully zero'ed out original file "/home/db19c/oradata/ORCLSTBY/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz83b9x_.dbf"
2026-01-20T10:50:08.012125-07:00
ORCLPDB1(3):Successfully deleted original file "/home/db19c/oradata/ORCLSTBY/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npz83b9x_.dbf"
2026-01-20T10:50:08.088219-07:00

NOTE: This same process occurs when rekeying also.

26ai New feature : DB_RECOVERY_AUTO_REKEY 

ON, which is the default for the standby, enables the standby to automatically perform an online tablespace rekey operation as part of the standby media recovery process. Be aware that this setting pauses media recovery. If the tablespace is large, then you could observe extended standby apply lag.

OFF, which is the default for the primary, does not perform a tablespace rekey operation. This setting enables an extended standby database to avoid lag time during an online conversion, and is designed for large Oracle Data Guard tablespace deployments. This enables the standby recovery to only record the tablespace key information but not perform the rekey operation inline. In the V$ENCRYPTED_TABLESPACES dynamic view, after the STATUS column value for the corresponding tablespace becomes REKEYING or ENCRYPTING on the standby database, then you can use a standby SQL session to issue an ALTER TABLESPACE ENCRYPTION ONLINE FINISH REKEY|ENCRYPT command to perform the rekey in parallel of media recovery. 

Observation #2 - When encrypting/rekeying a tablespaces, the original datafiles are overwritten with zeros to ensure they no longer contain any usable data.

Backing up newly encrypted database


I am now going to perform a new Level 1 backup of the database, and look to see what is being backed up. Below is the output from Block changed tracking showing the blocks being backed up.

    FILE# INCREMENTAL_LEVEL COMPLETION_TIME       BLOCKS DATAFILE_BLOCKS PCT_CHANGED
---------- ----------------- ----------------- ---------- --------------- -----------

Level 0 backup of datafiles
        13                 1 01-20-26 10:30:00    1793783         1894528       94.68
        14                 1 01-20-26 10:27:31    1081471         1125744       96.07
        15                 1 01-20-26 10:28:43    1368079         1419632       96.37
        16                 1 01-20-26 10:29:32    1573511         1676800       93.84

Level 1 backup of datafiles prior to encryption
        13                 1 01-20-26 10:30:15          1         1894528           0
        14                 1 01-20-26 10:30:15          1         1125744           0
        15                 1 01-20-26 10:30:15          1         1419632           0
        16                 1 01-20-26 10:30:15          1         1676800           0

Level 1 backup of datafiles post encryption
        13                 1 01-20-26 11:12:14          1         1894528           0
        14                 1 01-20-26 11:12:16          1         1125744           0
        15                 1 01-20-26 11:12:15          1         1419632           0
        16                 1 01-20-26 11:12:14          1         1676800           0
What you can see is that as far as RMAN is concerned, since this database is idle, only the header block changed.  RMAN did not backup the datafile blocks even though every block changed through the encryption process. Only the user contents of the blocks changed not the metadata about the block.

This is a critical observation.  
  • If you perform a weekly full/daily incremental backup, you will need a new Level 0 backup to ensure the datafiles are encrypted in your backup.
  • If you utilize the 9i "incremental merge" process, your backup will not be encrypted.  If you perform a "switch to copy", your datafiles will not be encrypted.  After encrypting, you must restart this strategy with a new full backup.
NOTE: One of the features of the ZDLRA is that it is "encryption aware", and you will not need to perform a new Level 0 backup to ensure you restore encrypted datafiles.

Observation #3 - The database does not recognize the blocks as changed.  The block header information, containing SCN information, and other metadata remains untouched. 


Datafile/Tablespace information 

Original Datafiles

Tablespace Name    FILE_ID File Name                      Size
--------------- ---------- ------------------------------ ----------
ENCTEST                 13 o1_mf_enctest_npz8393s_.dbf     14.454 GB
ENCTEST                 14 o1_mf_enctest_npz8gvz0_.dbf      8.589 GB
ENCTEST                 15 o1_mf_enctest_npz8oy0p_.dbf     10.831 GB
ENCTEST                 16 o1_mf_enctest_npz8yr6p_.dbf     12.793 GB

New Datafiles

Tablespace Name     FILE_ID File Name                      Size
--------------- ---------- ------------------------------ ----------
ENCTEST                 13 o1_mf_enctest_npzhqh0w_.dbf     14.454 GB
ENCTEST                 14 o1_mf_enctest_npzj2gdb_.dbf      8.589 GB
ENCTEST                 15 o1_mf_enctest_npzj9f4k_.dbf     10.831 GB
ENCTEST                 16 o1_mf_enctest_npzjl4dz_.dbf     12.793 GB

Tablespace encryption Status

PDB Name   Tablespace Name Enc.  Enc. alg   Master Key ID             Key ID                              tablespace Encryt key (trunc)
---------- --------------- ----- ---------- ------------------------- ----------------------------------- ------------------------------
ORCLPDB1   SYSAUX          NO               AawCP+ykIE/2v9kPpgqvHOk=  AC023FECA4204FF6BFD90FA60AAF1CE9    0C836501DE2C28286F4DFF45EDB563
           SYSTEM          NO               AawCP+ykIE/2v9kPpgqvHOk=  AC023FECA4204FF6BFD90FA60AAF1CE9    0C836501DE2C28286F4DFF45EDB563
           TEMP            NO               AawCP+ykIE/2v9kPpgqvHOk=  AC023FECA4204FF6BFD90FA60AAF1CE9    0C836501DE2C28286F4DFF45EDB563
           UNDOTBS1        NO               AawCP+ykIE/2v9kPpgqvHOk=  AC023FECA4204FF6BFD90FA60AAF1CE9    0C836501DE2C28286F4DFF45EDB563
           USERS           NO               AQAAAAAAAAAAAAAAAAAAAAA=  00000000000000000000000000000000    000000000000000000000000000000
           ENCTEST         YES   AES128     AawCP+ykIE/2v9kPpgqvHOk=  AC023FECA4204FF6BFD90FA60AAF1CE9    604F0A3F91F73875D0BC9325FA87C3

Above, you can see that a newly encrypted datafile copy was created for each  datafile member of the tablespace. The size, is exactly the same as the original datafile.  You can also see that since I didn't specify a specific algorithm, the tablespace was encrypted as AES128 (the default).

Observation #4 - A new datafile copy is created for each member. You need to make sure that there is enough space for a second copy of largest datafile.

Re-encrypted tablespaces from AES128 to AES256

The next process I am going to go through is common as customers rekey existing tablespaces from AES128 to utilize the AES256 encryption algorithm.
In this example, I am not only going to re-encrypt the tablespaces, I am also going to crash the database in the middle of this process to see how to handle this possibility.

SQL> alter tablespace ENCTEST ENCRYPTION ONLINE USING 'AES256' rekey;

For this example, I monitored the alert log and watched it encrypt the datafiles, as soon as it finished encrypting the first datafile (File# 14), I performed a "Shutdown Abort" on the database.

Primary Alert log
ORCLPDB1(3):About to rekey tablespace ENCTEST (tsn 3/6)
2026-01-20T11:46:45.353069-07:00
ORCLPDB1(3):TDE converting datafile /home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqh0w_.dbf (13) to /home/db19c/oradata/                      ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_%u_.dbf
2026-01-20T11:51:50.367605-07:00
ORCLPDB1(3):Blocks TDE converted for file /home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzmdoc8_.dbf size 1894528
2026-01-20T11:51:50.415541-07:00
ORCLPDB1(3):TDE convert operation committed for file /home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzmdoc8_.dbf
2026-01-20T11:51:52.481666-07:00
ORCLPDB1(3):About to zero out original file "/home/db19c/oradata/ORCLCDB/ORCLCDB/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqh0w_.dbf"
2026-01-20T11:52:25.125992-07:00
Shutting down ORACLE instance (abort) (OS id: 827465)
2026-01-20T11:52:25.158712-07:00
Shutdown is initiated by sqlplus@bgrenn-19-28 (TNS V1-V3).
License high water mark = 12
USER (ospid: 827465): terminating the instance
2026-01-20T11:52:26.213187-07:00
Instance terminated by USER, pid = 827465
2026-01-20T11:52:27.343819-07:00
Standby Alert log
ORCLPDB1(3):TDE converting datafile /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqj8h_.dbf (13) to /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_%u_.dbf
2026-01-20T11:51:51.143252-07:00
ORCLPDB1(3):Blocks TDE converted for file /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzmdphy_.dbf size 1894528
2026-01-20T11:51:51.150126-07:00
ORCLPDB1(3):TDE convert operation committed for file /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzmdphy_.dbf
2026-01-20T11:51:53.202013-07:00
ORCLPDB1(3):About to zero out original file "/home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqj8h_.dbf"
2026-01-20T18:52:25.254096+00:00
 rfs (PID:823518): Possible network disconnect with primary database
2026-01-20T18:52:25.258563+00:00
 rfs (PID:823518): while processing B-1209738101.T-1.S-412 BNUM:110516 BCNT:1
2026-01-20T18:52:25.259701+00:00
 rfs (PID:823516): Possible network disconnect with primary database
 rfs (PID:823518): Current process action IDLE, elapsed idle time 0
2026-01-20T18:52:25.266055+00:00
 rfs (PID:823516): while processing B-1209738101.T-1.S-412 BNUM:0 BCNT:0
2026-01-20T18:52:25.267216+00:00
 rfs (PID:823518): RFS client ASYNC ORL SINGLE (PID:823296)
2026-01-20T18:52:25.268790+00:00
 rfs (PID:823516): Current process action IDLE, elapsed idle time 32
 rfs (PID:823516): RFS client GAP MANAGER (PID:822694)
2026-01-20T11:53:04.841560-07:00
ORCLPDB1(3):Successfully zero'ed out original file "/home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqj8h_.dbf"
2026-01-20T11:53:06.478227-07:00
ORCLPDB1(3):Successfully deleted original file "/home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzhqj8h_.dbf"
2026-01-20T11:53:06.486711-07:00
ORCLPDB1(3):TDE converting datafile /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzj2j4t_.dbf (14) to /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_%u_.dbf
2026-01-20T11:54:47.101862-07:00
ORCLPDB1(3):Blocks TDE converted for file /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzmrlhf_.dbf size 1125744
2026-01-20T11:54:47.108829-07:00
ORCLPDB1(3):TDE convert operation committed for file /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzmrlhf_.dbf
2026-01-20T11:54:49.120370-07:00
ORCLPDB1(3):About to zero out original file "/home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzj2j4t_.dbf"
2026-01-20T11:55:28.313091-07:00
ORCLPDB1(3):Successfully zero'ed out original file "/home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzj2j4t_.dbf"
2026-01-20T11:55:37.980759-07:00
ORCLPDB1(3):Successfully deleted original file "/home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzj2j4t_.dbf"
2026-01-20T11:55:37.989404-07:00
ORCLPDB1(3):TDE converting datafile /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_npzj9kff_.dbf (15) to /home/db19c/oradata/ORCLCDB/ORCLSTBY/3CE209FE44CDECAEE06394A5500AE99C/datafile/o1_mf_enctest_%u_.dbf

What is most interesting in the alert logs, is that the standby continued to rekey the datafiles for the tablespace.  This occurred independently of the primary.

Observation #5 - The primary sends the ALTER DATABASE REKEY command in the redo, and the standby database performs the process independently. even once the primary crashed.

Startup Database after crash

After starting up the primary database I took a look at the encryption status of the tablespace in both the primary and standby.. In the primary it shows as "REKEYING", the standby successfully finished the operation and shows as normal AES256 encrypted


select ts#,
       ENCRYPTIONALG,
       ENCRYPTEDTS,
       status,
       con_id
from v$encrypted_tablespaces;

Primary Database (aborted)

      TS# ENCRYPT ENC STATUS         CON_ID
---------- ------- --- ---------- ----------
         6 AES256  YES REKEYING            3

Standby Database (continued operation)

      TS# ENCRYPT ENC STATUS         CON_ID
---------- ------- --- ---------- ----------
         6 AES256  YES NORMAL              3

Now I am going to look at the datafiles 
-rw-r-----+ 1 oracle oracle 15519981568 Jan 20 11:52 o1_mf_enctest_npzhqh0w_.dbf
-rw-r-----+ 1 oracle oracle  9222103040 Jan 20 12:10 o1_mf_enctest_npzj2gdb_.dbf
-rw-r-----+ 1 oracle oracle 11629633536 Jan 20 12:10 o1_mf_enctest_npzj9f4k_.dbf
-rw-r-----+ 1 oracle oracle 13736353792 Jan 20 12:10 o1_mf_enctest_npzjl4dz_.dbf
-rw-r-----+ 1 oracle oracle 15519981568 Jan 20 12:10 o1_mf_enctest_npzmdoc8_.dbf
Since I aborted the database, while it was "zeroing out the datafile" there are two copies of the datafile.
At this point since it started the rekey operation, my only choice is to "FINISH" the operation. This is a manual step to restart the process.

alter tablespace ENCTEST ENCRYPTION FINISH rekey;

Observation #6 - Once you start an encryption operation, it must finish. There is no backing out.

Once the rekey operation finished, I again looked at the datafiles.  I can see that the original datafile that was in process when I aborted the database is still there. If an online encryption operation is in process during a crash, you might have an orphan file from the process that has to be manually deleted.

-rw-r-----+ 1 oracle oracle 15519981568 Jan 20 11:52 o1_mf_enctest_npzhqh0w_.dbf
-rw-r-----+ 1 oracle oracle 15519981568 Jan 20 12:10 o1_mf_enctest_npzmdoc8_.dbf
-rw-r-----+ 1 oracle oracle  9222103040 Jan 20 12:27 o1_mf_enctest_npzopwfg_.dbf
-rw-r-----+ 1 oracle oracle 11629633536 Jan 20 12:30 o1_mf_enctest_npzovdhd_.dbf
-rw-r-----+ 1 oracle oracle 13736353792 Jan 20 12:34 o1_mf_enctest_npzp0zd5_.dbf






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Tuesday, October 28, 2025

Configuring Cloud Protect

 Cloud Protect is a new offering announced at AI World 2025.  Cloud Protect allows you to leverage the Oracle Database Zero Data Loss Autonomous Recovery Service for your on-premises Linux x64 databases.  Cloud Protect even allows you to enable real-time redo.


You can find a great blog post by Kelly Smith announcing it here,  and you can find the detailed documentation here.

I've been testing it out for the past week and I wanted to share everything I learned about using it.

First, there are a few things to understands about Cloud Protect Version 1.

  1. You can only restore the database back to the original host/cluster you configured backups from.  All nodes in a RAC cluster can be used for restoration.
  2. Cloud Protect can only be used from non-ExaCC on-premises databases.
  3. You cannot use a dual point-in-time backup strategy.  Cloud Protect must be your primary backup location.
Read more »
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Monday, October 6, 2025

ZDLRA best practices

 ZDLRA best practices (updated 2025)

I have seen a lot of changes with the ZDLRA over the last 10 years or so, and because of that I wanted to document the best practices to follow that changed up to now, and are also helpful for new existing. (2025).



Because of the changes that have occurred as the product has matured, I wanted to write a blog post on what existing customers should think about doing now, and what new customers should think about.

1. Channel Configuration

There are a few items to talk about with channel configuration. First let's break down the pieces of the channel configuration


a) Library

Version

Up until version 19.26, you could use a shared version of the library (libra.so) based on the OS.  Updates to the library could be downloaded directly from MOS.

Starting with version 19.27 on Linux, you must use the version that is stored in $ORACLE_HOME and patched using OPatch.  More information can be found in the MOS note below.

Location (channel setting)

In the previous section I mentioned that the library is tied to the version of Oracle starting with 19.26. Prior to this release, the default channel setting for the library with the ZDLRA  was
  • "PARMS  'SBT_LIBRARY=$ORACLE_HOME/lib/libra.so"
In order to always utilize the current library for the $ORACLE_HOME, the recommendation is to set the channel setting to
  • "SBT_LIBRARY=libra.so" - No path, and it will default to the current $ORACLE_HOME/lib"
    Or
  • "SBT_LIBRARY=oracle.zldlra" - This will default to the current $ORACLE_HOME/lib/libra.so

b) Environment

In the environment section, you specify the SEPS wallet location. Because there could be conflicts with other oracle products that use a wallet (like OUD), the default location for the SEPS wallet should be set to the WALLET_ROOT location, rather than within the $ORACLE_HOME location.

In the past,  the channel setting for ZDLRA  was
  • "RA_WALLET=location=file:${ORACLE_HOME}/dbs/ra_wallet credential_alias={SEPS entry in wallet}"
The recommendation is to set the WALLET_ROOT in the spfile, and store the SEPS wallet within the server_seps directory under this location. If WALLET_ROOT is set to $ORACLE_BASE/admin/{$DB_NAME}/wallet, the setting would be

  • "RA_WALLET=location=file:${ORACLE_BASE}/admin/${DB_NAME}/wallet/server_seps/ credential_alias={SEPS entry in wallet}"

c) TLS or non-TLS

If a customer has the ZDLRA configured to encrypt backups with TLS/SSL, the library, by default, will attempt to encrypt the backup using SSL/HTTPS.  If TLS/SSL is configured as optional, and if the client does not have the certificate information, backups will fail. To avoid this, it is recommended to add the following setting to the channel configuration.  This setting will allow you to send backups even if optional TSL/SSL is configured.

  • _RA_NO_SSL=TRUE

d) Space Efficient Encrypted Backups

In order to use Space Efficient Encrypted Backups, you must set the following in your channel configuration. This is only available on linux with DB version 19.18+. Keep in mind this setting will only compress datafile backup pieces.  
  • RA_FORMAT=TRUE

Example:

RMAN> CONFIGURE CHANNEL DEVICE TYPE 'SBT_TAPE' PARMS  'SBT_LIBRARY=oracle.zdlra,ENV=(_RA_NO_SSL=TRUE,RA_WALLET=location=file:/u01/app/oracle/admin/orcl/wallet/server_seps credential_alias="tcps://pmdra1-scan1.us.oracle.com:2484/ra1db", RA_FORMAT=true)';

  • oracle.zdlra - Use the libra.so from the $ORACLE_HOME for the database
  • _RA_NO_SSL=TRUE - Do not send backups encrypted if TLS is optionally enabled. 
  • /u01/app/oracle/admin/orcl/wallet/server_seps - Wallet location from WALLET_ROOT
  • RA_FORMAT=true - Use space efficient encrypted backups


2. RMAN encryption

One misconception with Space Efficient Encrypted Backups, is that by setting RA_FORMAT=TRUE you are both compressing and encrypting backups. This is not true. You are only compressing the backups. If the tablespace is encrypted with TDE, the backup will remain encrypted, but any non-TDE tablespace backups will be unencrypted.  In order to encrypt the backup pieces (Datafiles, controlfile,. archive logs and spfile) you need to both set an encryption key (if not already set), and set RMAN encryption on.  If you are backing up any tablespaces that are not TDE, you must also ensure you set RA_FORMAT=TRUE.
You should also set the default encryption algorithm to AES256, as most customers use this today rather than the default of AES128

NOTE: Use of RA_FORMAT=TRUE (RMAN Compression) and RMAN encryption is included in the license for ZDLRA and you do not need the ACO or ASO license for backups to the ZDLRA.

3. Real-time redo settings.

a) Default SEPS wallet location


Wallets are becoming more and more common with databases, and this increases the chances that there will be conflict with other Oracle features that also utilize a wallet. To avoid this there is a new default location for the SEPS wallet used by real-time redo. The database will first look in the {WALLET_ROOT}/server_seps location for the wallet.  It is recommended to set the WALLET_ROOT for all databases and use this default location for the SEPS wallet.  Of course you may use links to simplify management.

b) Encrypt Redo


If you have an encryption key set, and you wish to fully encrypt your backups, you also need to ensure that real-time redo is also encrypted. You need to set encryption on the destination for real-time redo
  • ENCRYPTION=ON

NOTE: As an additional note, I have a previous blog post on wallets you can find here.  I have worked with a few customers that have run into issues configuring real-time redo because they have other products that are affected by WALLET_OVERRIDE=TRUE.  What I tell customers is that  if they want to continue to use the SEPS wallet for RMAN scripts (i.e. rman target / catalog /@{wallet entry}), then they should create a separate/customer sqlnet.ora file in a different location, and set TNS_ADMIN in their RMAN backup script. 

4. Reserve Space

Reserve space has been difficult to explain, and it has become even more important when implementing a compliance window.  If there is no compliance set, then the reserve space is only interrogated when the ZDLRA runs out of space.  When a compliance window is set, the reserve space is interrogated when backing up to ensure that compliance locked backups fit within the reserved space. If they do not, backups are rejected.  Because of this, I always recommend setting the "auto-tune reserve space" for the policies, especially when setting a compliance window. This setting will automatically adjust the reserve space for you as databases grow.

5. When encrypting backups set "secure mode"

If you need to fully encrypt your backups with RMAN encryption, it is recommended to use "secure mode" on your protection policy. This setting checks all backup pieces (including real-time redo) to ensure that they are RMAN encrypted.  Any unencrypted backup pieces will be rejected.

6. Use racli commands

One of the biggest changes is the increase in the functionality available with racli command vs executing DBMS_RA PL/SQL packages. It is recommended to utilize RACLI commands when possible.  I know when trying to automate onboarding databases, it is much easier to utilize PL/SQL packages.

7. Pair ZDLRAs when using replication

Another change is the ability to pair ZDLRAs that have replication configured. This can be done with the "racli add ra_partner" command.  Using the ZDLRA pairing commands for replication greatly simplifies the configuration of replication. Existing configurations can be converting to using the pairing model.

8. Review types of DB users

There have been a few changes to DB users. There are now 4 types of DB users.
  • ADMIN -Used to administer ZDLRA configuration settings
  • MONITOR - Read-only account that can view metadata
  • REPLICATION - Used to replicate backups between ZDLRAs
  • VPC - Used by protected databases to send/received backups
    • Insecure=TRUE - VPC user's password will expire, but it can be reset to the same password. This type of user does not support password rollover. Alternately you can set the profile of the VPC user to "NO_EXPIRE". This is less secure, but avoids having the password expire.
    • insecure=false - VPC user's password will expire, but this user can leverage password rollover (STIG) to manage password rotation without having backups fail.
NOTE: If you need to rotate password for VPC users you should leverage the STIG/password rollover function that allows you have two passwords associated with the same VPC user as you update wallets.

Summary:

  1. Set WALLET_ROOT in the database and store the SEPS in the {WALLET_ROOT}/server_seps directory
  2. Ensure the library location in the channel configuration defaults to the current $ORACLE_HOME
  3. Set _RA_NO_SSL=TRUE to ensure that converting to TLS/SSL will not cause existing backups to fails
  4. Set RA_FORMAT=TRUE to leverage space efficient encrypted backups --> Linux only
  5. Enable RMAN encryption, and set algorithm to AES256 --> Linux only
  6. Encrypt Real-time redo if applicable
  7. If you require fully encrypted backups, set SECURE_MODE on the policy
  8. Enable auto-tune of reserved space for all databases, especially those using a compliance window.
  9. Use RACLI commands to manage the ZDLRA
  10. Pair ZDLRAs when configuring replication
  11. Leverage password rollover for VPC users if you require password rotation



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