Exadata is Oracle’s brand name for their technology involving database appliances that include storage servers with built-in database intelligence. Oracle is a US-based database vendor.

This page is a collection of my Exadata related postings.

Exadata Part I: Smart Scan

Exadata Part II: Storage Index

Exadata Part III: Compression

Exadata Part IV: Flash Cache

Exadata Part V: Monitoring with Database Control

Exadata Part VI: Cell Administration with dcli


No DISK_REPAIR_TIME on Exadata Cells

Invisible Indexes & Exadata

Exadata Part VII: Meaning of the various Disk Layers

Important Statistics & Wait Events on Exadata

Replacing a damaged Hard Disk on Exadata Cells


Exadata Quarter Rack Architecture Picture

LunchTimeLVC (Smart Scan – What is so smart about it)

Accelerated space reclamation on Exadata Cells

Exadata X3 Key Points

Appliance? How #Exadata will impact your IT Organization

Why Write-Through is still the default Flash Cache Mode on #Exadata X-4

Exadata Patching Introduction


Google by Uwe Hesse

  1. #1 von Eric Y am Juli 23, 2011 - 04:21

    Thank you for sharing your knowledge and helping everybody get better at Exadata.

  2. #2 von Uwe Hesse am Juli 29, 2011 - 16:18

    You’re welcome, Eric 🙂

  3. #3 von Andrés am August 30, 2011 - 23:18


    Is there anyway to install exadata on VM, i just want to learn and improve on it?.

    What do u recommend me to learn exadata.



  4. #4 von Uwe Hesse am September 1, 2011 - 18:33


    we have indeed an Exadata VM, but it is restricted for internal use only at this time, sorry.

    Learning Exadata: Additionally to the OU class

    there are some good sources in the web. Look at my LINKS list on the right, for example.

    Look at Jonathan Lewis‘ collection of Exadata Links here:

  5. #5 von Andrés am September 2, 2011 - 00:10

    Hi, for Oracle employees still this Vm restricted?

  6. #6 von Uwe Hesse am September 2, 2011 - 02:48

    No. If you are an Intern, write me an email and I give you the intranet-link where to download it.

  7. #7 von Andrés am September 2, 2011 - 21:50

    Hi Uwe, i already send you the email.



  8. #8 von alexandruneda am Februar 24, 2012 - 20:31

    You made Exadata too simple for us!
    Thanks for having this course in Bucharest and keep this blog going because it’s very useful!

  9. #9 von Uwe Hesse am Februar 27, 2012 - 15:38

    Thank you, Alexandru, for the nice feedback and the good company during the last week! It was a pleasure for me to deliver that course 🙂

  10. #10 von robin chatterjee am Februar 28, 2012 - 11:12

    Hi uwe,
    I am trying to figure out how updates to HCC compressed data work. I assume that the whole cu is locked,the required row is marekd as deleted from the cu and then a normal block with the updated row is added to the table ?

    otherwise if the whole cu has to be decompressed and recompressed then there wouln’t be a need to reorganise the hcc tables periodically in order to fix this issue. is there any way to empirically test this ( maybe by using rowids ?)

  11. #11 von Uwe Hesse am Februar 28, 2012 - 12:01

    Hi Robin, indeed, during an update of a row inside a HCC compressed table, the whole Compression Unit (CU) is locked and the row will be migrated outside of that CU into a Block with OLTP compression. It is therefore not recommended to use HCC for tables that will get many updates.

  12. #12 von Satya am Juni 19, 2012 - 15:32

    Hi Uwe,

    Thanks for sharing the knowledge…


  13. #13 von raj am Juni 22, 2012 - 13:47

    Hi ,

    Can i have the syntax of user creation in exadata machine

  14. #14 von robin chatterjee am Juni 22, 2012 - 19:23

    standard oel commands such as useradd work….

  15. #15 von raj am Juni 23, 2012 - 05:03

    1)for example…the user creation will be as…create user username identified by password .Am i rite?
    2)Could you please list down the administartion tasks that is to be carried from dba perspective in exadata machine apart from normal oracle db activities

  16. #16 von Uwe Hesse am Juni 23, 2012 - 17:01

    The DBA tasks on an Exadata Database Node are the very same as on other Linux platforms. Especially the Database Layer is identically as on other Platforms – it is an ordinary Oracle Database

    There are some special tasks on the Exadata Storage Server Layer – the question is whether DBAs or SysAdmins /Storage Admins are supposed to do that on your site

  17. #17 von robin chatterjee am Juni 23, 2012 - 19:37

    Not sure what you mean by adding a user to the Exadata machine… If you need to add a user to a specific instance you would use the standard oracle db commands for that instance/database. If you need to add a user to the compute nodes you need to use Oracle Enterprise Linux standard commands. I do not consider creation of a user in a Database to be Exadata specific. If you are just a DBA on Exadata then who does the sysadmin tasks ? I would suggest your looking into the book „Expert Oracle Exadata“ to get a good feel of all the aspects specific to Exadata. If you are so inclined there is no reason why you cannot learn the Delta tasks necessary to take complete care of an Exadata machine.

  18. #18 von Jesmond am Oktober 24, 2012 - 21:13

    With reference to Oracle VM on Exadata, is this available, or are there any plans to release oracle VM on Exadata?

  19. #19 von Rajesh GN am November 21, 2012 - 17:12

    Hi ,

    Could you please explain me the oracle private cloud that what is it? Does it steal my job?

    Many Thanks
    Rajesh GN

  20. #20 von A K am September 17, 2013 - 07:18


    If I have enabled the compression then if any new data will come that automatically will compressed or we have to do something.

    A K


  21. #21 von Uwe Hesse am September 17, 2013 - 15:34

    It depends on the compression type. With OLTP compression, simple inserts will go optimally compressed. With basic or HCC compression, you need the /*+ append */ hint to get the best compression ratio.

  22. #22 von Mark am November 26, 2013 - 03:00

    Hello Uwe,

    I have been asked to work with an engineering team to design Disaster Recovery and COOP sites.

    Goal: Maximize data through put.
    Environment: several exadata with massive SL6000 tape libraray and massive SAN storage at all sites.

    Question: Can you point me to Oracle or EMC references?

  23. #23 von dbaesp am Januar 18, 2014 - 14:20

    Hi Uwe,
    you cannot share the Exadata VM of Oracle Education, but can I build my virtual exadata test environment for OCE prep ?
    Actually I already did that (waiting for the real Exadata that will be up&running on February), but if needed I’ll erase all the VMs.
    Could you eventually guide me to the official Oracle view on this question ?
    Eugenio /*+ esp */

  24. #24 von Uwe Hesse am Januar 25, 2014 - 21:04

    Eugenio, I think the official view on this topic is that the Exadata (Storage Server) Software is allowed to use only on Oracle Exadata Database Machine.

  25. #25 von dbaesp am Januar 26, 2014 - 10:19

    Thanks Uwe.

  26. #26 von karthik am Januar 29, 2014 - 16:30

    Hello Uwe,

    Can you send me the Oracle Intranet link to download the Exadata vm.


  27. #27 von Exadata am März 5, 2014 - 15:29

    Which is the best strategy to do compression on OLTP and DW?


  28. #28 von Carlos Anibal Amaral de Carvalho am März 28, 2014 - 03:57

    Hi Uwe,

    Just a quick question, as we are now on Exadata X4 family, what will happen to the 1Z0-027 Certification? Will Oracle provides an Exadata Machine Administrator X4 too?


  29. #29 von Edgardo am April 15, 2014 - 21:57

    Oracle Certification: This exam, Oracle Exadata X3 Administration, has been updated for Oracle Exadata X4.

    Now: Oracle Exadata X3 and X4 Administration
    Exam Number: 1Z0-027
    Exam Product Version: Exadata,
    Exam Price: US$ 245 More on exam pricing

    Duration: 150 minutes
    Number of Questions: 90
    Passing Score: 60% View passing score policy
    Validated Against:
    This exam has been validated against Oracle Database 11g, Oracle Database 12c, Exadata Database Machine X3 and X4, and cell images, and
    format: Multiple Choice

    Edgardo C.

  30. #30 von Venkat am Juli 13, 2014 - 19:28


    Can you please share Exadata vm, I am just having little knowledge and i want learn more about the Exadata .

    Thanks you very much for sharing.

  31. #31 von Unnat am Juli 29, 2014 - 08:48

    Hi Uwe,

    I am interested in learning Exadata. is it possible that I can get Exadata machine/vm access ? Please provide if there is any.



  32. #32 von Uwe Hesse am Juli 31, 2014 - 08:46

    Guys, unless you are Oracle employees, I cannot help you with that, because we are not allowed to give our Exadata VM to externs. Sorry about that!

  33. #33 von Rakesh Tripathi am Oktober 13, 2014 - 16:50

    Hi Uwe,

    I understand Exadata VM cannot be shared for download at this time by general users outside Oracle Corporation.

    (a) Is there any thought process in making this available to wider public (assuming there are any technical / intellectual property blockers) ? I appreciate that many other simulators / VM images are made available for customers/partners/general public so was wondering if there are any blockers at this time which we can hope to have addressed in future…

    (b) Is there a feasibility that this can be made available as a „hosted“ facility (much like what is done during OPN/OU courses) for a timeboxed duration with Oracle charging for that use?



  34. #34 von foundation_ww am Juni 20, 2015 - 00:28

    Hello Uwe,

    In regards to Oracle Exadata on VM… everything is possible you just need to set as priority number one!!!!

    – Oracle Provide Exadata as VM environment on Oracle VM 222 during Exadata Trainings.. – True!!!!
    – Oracle has official download possibility on edelivery.oracle.com ( in the past all cell software has password … but in our days.no ) which is good 🙂 – True….
    – Oracle create Exadata Technology in order to be able to give move performance to the world… but!!! if you don’t have that at home 🙂 in order to learn more and more you are not going to be up-to-date with technology and the only possibility is to read blogs like this or start in the Company with Exadata……. but how to test… maybe the best option is to test on Production… great!!!!

    So, i don’t agree with your feedback to all other people here.. that Exadata VM is only for internal use.
    Maybe this is Oracle internal procedure that you should not share internal information…

    You should try to become in our shoes… when you as Oracle Guru has all necessary access to learn all what you need is very easy!!! but when you don’t …. then you start to think why? and how to get such access….

    But… let me put on this way… in order to access internal links you just need to have valid oracle account for any kind of trainings 🙂
    This mean that if you like to perform full network scan.. no issues… also all user/pass are the same ( part of training documentation )

    Also as you know when you run Exadata cell software on non-oracle HW you will get message like
    makeModel:-Fake hardware…but this is not an issues.. all information are part of the scripts and information about HW can be mask with special changes on the script in order to change that message….:) so if oracle add an option „Fake hardware“ as possibility.. what is the restriction…

    PS: Technology is powerful when we know how its work and how to implement in a very useful way…. if you don’t know… you have to pay for trainings or to pay on consultants.. great!!! but why? all information should be available for the community in order to bring all benefits!!!

    Also I have very bad experience with a lot of Oracle consultants related to Oracle Exadata implementation.. after that we should rework all implementation. So… experience is the point… when you don’t have such… you should create training environment for your own technology testing..


  35. #35 von sql am Oktober 28, 2015 - 06:33

    Hi All,

    If you want to monitor and observe exadata’s performance, you can use ExadataViewer.
    You can use it on your real machine or virtual machine, just install it on one of your db node.

    Through a set of realtime graphical views, you can observe:
    1) Exadata’s internal architecture
    2) Physical I/O dataflow in the cells
    3) Exadata new features‘ offloading efficiency (smart scan, storage index, ehcc, flash cache, writeback)
    4) Db & cell hosts‘ CPU usage & I/O throughtput
    5) Top SQLs
    6) The relationship between top SQLs, CPU and I/O


  36. #36 von rajendra am April 3, 2016 - 22:07

    are exadata VM available now … I want to install on my pc and feel the actual environment 🙂

  37. #37 von Edward am September 6, 2017 - 12:11

    Hi Uwe…I want to create a 2.5TB filesystem on my compute node…but I only have 300GB left on my vgexadb…how/where can I get the rest of the storage I need to accomplish this? Thanks and all the best!

  38. #38 von Pradeep Kumar am Oktober 31, 2018 - 14:16

    How can i configure exadata on vmware for practice purpose. please help with some gud link or steps.
    Many thanks

  39. #39 von Robin Chatterjee am November 5, 2018 - 09:33

    There is no legal way to do so… only customers with a valid exadata support contract have access to the exadata storage software that you would need to create a simulator for exadata. Also given exadata minimum requirements you would need a machine with around a terabyte of RAM in order to simulate 3 storage cells and 2 database nodes.

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