This is the first part in a series of blog posts on TDE.
Many organizations are moving to TDE, and this can have a dramatic affect on your systems.
TDE impacts 2 areas
1) Post encryption compression goes away. Encrypted data can’t be compressed. Now why do I mention “Post encryption” ? This is because data can be compressed before encrypting. Compressed data in your database (HCC, OLTP, basic etc.) is compressed PRIOR to encryption. Utilizing compression in your database not only saves you disk space on your storage system, but it also saves you disk space for your backups. The loss of compression post encryption can have many consequences you might not immediately think of
- if you are using SSD storage that compresses blocks, you need to take into account the extra storage needed
- If you are using a De-duplication appliance you will lose most of the benefits of de-duplication.
- If you are compressing your backups, you will lose the benefits gained from compression (small backups and lowered network traffic).
2) Moving to TDE requires more space during the migration. Rebuilding the tablespaces with a newly encrypted copy is done by creating a second copy of each datafile (encrypted), and then removing the pre-encrypted copy. The database switches to the new datafile when the process is complete. This utilizes additional storage for the second copy of the datafiles. The other migration impact is an increase in backup storage. After encrypting tablespaces, a new level 0 backup is needed to ensure you are restoring to an encrypted copy of the data. Remember the encryption process changes all the blocks in the datafiles. I will discuss the backup implications more later.
Now I’m going to start by describing the dataset I used for testing.
In order to create this dataset I used the oewizard from Swingbench
Here are the objects and the sizes.
SEGMENT_NAME SEGMENT_TYPE TABLESPACE_NAME SPACE_USED
------------------------------ ------------------ ------------------------------ -----------
CUST_EMAIL_IX INDEX SOE 975 MB
CARD_DETAILS TABLE SOE 2,048 MB
CUSTOMERS_PK INDEX SOE 443 MB
CARD_DETAILS_PK INDEX SOE 662 MB
PRD_DESC_PK INDEX SOE 0 MB
INV_WAREHOUSE_IX INDEX SOE 16 MB
ADDRESS_CUST_IX INDEX SOE 703 MB
ORD_SALES_REP_IX INDEX SOE 594 MB
ORD_CUSTOMER_IX INDEX SOE 671 MB
CUST_ACCOUNT_MANAGER_IX INDEX SOE 417 MB
ORDERENTRY_METADATA TABLE SOE 0 MB
ADDRESS_PK INDEX SOE 662 MB
ITEM_ORDER_IX INDEX SOE 2,000 MB
ADDRESSES TABLE SOE 3,392 MB
ORDER_ITEMS TABLE SOE 6,976 MB
ORDERS TABLE SOE 3,968 MB
PRODUCT_INFORMATION TABLE SOE 0 MB
LOGON TABLE SOE 1,728 MB
ORDER_PK INDEX SOE 632 MB
WHS_LOCATION_IX INDEX SOE 0 MB
PROD_CATEGORY_IX INDEX SOE 0 MB
CARDDETAILS_CUST_IX INDEX SOE 704 MB
INVENTORY_PK INDEX SOE 18 MB
CUST_FUNC_LOWER_NAME_IX INDEX SOE 683 MB
PRODUCT_DESCRIPTIONS TABLE SOE 0 MB
WAREHOUSES_PK INDEX SOE 0 MB
PRODUCT_INFORMATION_PK INDEX SOE 0 MB
ITEM_PRODUCT_IX INDEX SOE 1,768 MB
CUST_DOB_IX INDEX SOE 528 MB
PROD_NAME_IX INDEX SOE 0 MB
CUSTOMERS TABLE SOE 3,328 MB
WAREHOUSES TABLE SOE 0 MB
INVENTORIES TABLE SOE 176 MB
ORDER_ITEMS_PK INDEX SOE 2,234 MB
INV_PRODUCT_IX INDEX SOE 16 MB
ORD_ORDER_DATE_IX INDEX SOE 752 MB
ORD_WAREHOUSE_IX INDEX SOE 709 MB
PROD_SUPPLIER_IX INDEX SOE 0 MB
TOTAL 36,804 MB
Here is the total size for the data
TABLESPACE_NAME FILE_ID FILE_NAME SPACE_USED TOTAL_ALLOCATE TOTAL_FREE
------------------------------ ---------- ------------------------------ ----------- -------------- --------------
SYSTEM 1 814 MB 820 MB 6 MB
SOE 2 o1_mf_soe_fypolcvt_.dbf 3,468 MB 5,120 MB 1,652 MB
SYSAUX 3 606 MB 640 MB 34 MB
UNDOTBS1 4 80 MB 3,040 MB 2,961 MB
SOE 5 o1_mf_soe_fypo7tz7_.dbf 3,451 MB 5,120 MB 1,669 MB
SOE 8 o1_mf_soe_fyponrxc_.dbf 3,381 MB 5,120 MB 1,739 MB
SOE 9 o1_mf_soe_fypoq6d6_.dbf 3,373 MB 5,120 MB 1,747 MB
SOE 10 o1_mf_soe_fyposohg_.dbf 3,310 MB 5,120 MB 1,810 MB
SOE 11 o1_mf_soe_fypow57f_.dbf 3,275 MB 5,120 MB 1,845 MB
SOE 12 o1_mf_soe_fypoym9x_.dbf 3,255 MB 5,120 MB 1,865 MB
SOE 13 o1_mf_soe_fypp11qh_.dbf 3,256 MB 5,120 MB 1,864 MB
SOE 14 o1_mf_soe_fypp3jr0_.dbf 3,304 MB 5,120 MB 1,816 MB
SOE 15 o1_mf_soe_fypp61fl_.dbf 3,308 MB 5,120 MB 1,812 MB
SOE 16 o1_mf_soe_fypp8jp1_.dbf 3,423 MB 5,120 MB 1,697 MB
===================================================================================================================Total 38,303 MB 60,820 MB 22,517 MB
From above I can see that I am using 38 GB of space, out of the 61 GB of space allocated.
Now I created a backup set . With no compression the size of the backup set is about the size data used.
[oracle@oracle-server]$ ls -al
total 38910628
drwxrwx---. 2 oracle oracle 58 Nov 15 16:34 .
drwxrwx---. 3 oracle oracle 24 Nov 15 16:23 ..
-rw-rw----. 1 oracle oracle 39844478976 Nov 15 16:37 o1_mf_nnnd0_TAG20181115T163432_fyvsm8rz_.bkp
[oracle@oracle-server]$
Just to save my spot .I’m going to create a restore point to make this the starting point of all my testing.
SQL> create restore point new_database;
Restore point created.
Now let’s look at what happens when I compress the backup of this database
oracle oracle 39844478976 Nov 15 16:37 o1_mf_nnnd0_TAG20181115T163432_fyvsm8rz_.bkp ---> Original backup
oracle oracle 11424759808 Nov 15 17:09 o1_mf_nnndf_TAG20181115T165247_fyvtoj7m_.bkp ---> Basic Compression
oracle oracle 9468592128 Nov 15 18:33 o1_mf_nnndf_TAG20181115T174452_fyvxq4s2_.bkp ---> High Compression
oracle oracle 14488240128 Nov 15 18:44 o1_mf_nnndf_TAG20181115T183319_fyw0l08k_.bkp ---> Medium Compression
| Backup Method | Backup Size |
| No compression | 40 GB |
| Basic Compression | 11 GB |
| Medium Compression | 14 GB |
| High Compression | 95 GB |
My next Blog will cover taking this data set and encrypting it.