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what is SIS-Limited exactly? RRS feed

  • Question

  • What is the SIS-Limited feature that DPM installs on non-storage Windows Servers? I know what the normal SIS is, but I can't find any traces of that on my DPM server. There's no groveler service, no checkbox in the volume properties dialog to enable SIS, etc. I also know that it deduplicates on a file level, so why does DPM even need it? You can rarely find duplicate files on replica or recovery point volumes, they contain database images, Hyper-V images, BMR images, etc.
    Thursday, October 20, 2011 9:37 AM

Answers

All replies

  • Hi Fejesjoco,

    DPM uses SIS to optimize the storage space on the drives in the storage pool. SIS on DPM is not the same as SIS on storage server where you can activley see and work with it. So you wont see check-boxes on the volumes and be able to enable/disable like on a storage server.I have not seen it referred to before as SIS-Limited. I have only seen it refereed to as SIS. Part of the command you use to install it is SIS-Limited but I don't think this is what it is called.

    Here is a way you can confirm that it is installed and working properly on your DPM server you need to verify the SIS key exists: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SIS. If the SIS key is there then SIS is installed properly.

    HTH


    My Blog | www.buchatech.com | www.dpm2010.com
    Sunday, October 23, 2011 10:10 PM
    Moderator
  • The registry key exists but that can't be all. (It's called SIS-Limited by ocsetup.exe under the hood.)

    • there's no sisadmin command
    • there's no groveler service
    • there's no "sis common store" folder
    • and the real deal: I copied the same file with different names to a replica volume, and they both consumed the equal amount of space
    I can accept that it's installed by confirming there's a registry key, but what does it do? Does it do anything at all?
    Monday, October 24, 2011 7:29 PM
  • Hello,

    SIS filter is used by DPM to optimize the use of storage for the backups.  Although this is not directly discussed in the DPM portion of technet, here is an article that explains SIS a little better.

    http://technet.microsoft.com/en-us/library/dd573308(WS.10).aspx

    Thanks
    Shane
    Tuesday, October 25, 2011 1:42 PM
  • Hello,

    SIS filter is used by DPM to optimize the use of storage for the backups.  Although this is not directly discussed in the DPM portion of technet, here is an article that explains SIS a little better.

    http://technet.microsoft.com/en-us/library/dd573308(WS.10).aspx

    Thanks
    Shane

    Hi Shane,

    Thanks for the link. It has useful information but does not answer why the SIS services are not on the DPM server or how to manage the SIS-Limited. If DPM uses the SIS filter shouldn't there be a Single Instance Storage Filter service? I take it is not possible to manage SIS-Limited? If it possible where can we find more information about SIS-Limited?

    Regards,


    My Blog | www.buchatech.com | www.dpm2010.com
    Tuesday, October 25, 2011 5:02 PM
    Moderator
  • Hello,

    SIS filter is used by DPM to optimize the use of storage for the backups.  Although this is not directly discussed in the DPM portion of technet, here is an article that explains SIS a little better.

    http://technet.microsoft.com/en-us/library/dd573308(WS.10).aspx

    Thanks
    Shane

    I've seen that link already. The problem is that everyone keeps repeating what the well-known SIS is and that DPM needs a different kind of SIS, but noone seems to know what the latter is.
    Tuesday, October 25, 2011 6:01 PM
  • Hello,

    The management of SIS as far as I know is limited: http://technet.microsoft.com/en-us/library/dd573317(WS.10).aspx

    As far as why DPM needs it or uses it, the link to the MSDN site provided  http://msdn.microsoft.com/en-us/library/aa362506.aspx may offer a little better understanding as to why the developers decided to design DPM this way.

    "The advantages of using SIS and the SIS backup architecture are the following:

    • The connections between the SIS links and the backing files are automatically maintained by the SIS architecture as your backup applications call the SIS backup API functions.
    • The contents of the SIS reparse points are opaque to your backup and restore applications, ensuring that upgrades to the SIS internals will not require a change in the SIS API or your backup and restore applications that call SIS API functions. You need only recompile your application with a new version of the SIS DLL, named Sisbkup.dll.
    • Because SIS is implemented as a file system filter driver, it constantly tracks the connections between the SIS links and the backing files. When the files are backed up and restored, SIS backup ensures that only one instance of the backing file will be backed up and restored, regardless of the number of SIS links that point to it."

     

    Thanks
    Shane

    Wednesday, October 26, 2011 1:29 PM
  • Hello,

    The management of SIS as far as I know is limited: http://technet.microsoft.com/en-us/library/dd573317(WS.10).aspx

    As far as why DPM needs it or uses it, the link to the MSDN site provided  http://msdn.microsoft.com/en-us/library/aa362506.aspx may offer a little better understanding as to why the developers decided to design DPM this way.

    "The advantages of using SIS and the SIS backup architecture are the following:

    • The connections between the SIS links and the backing files are automatically maintained by the SIS architecture as your backup applications call the SIS backup API functions.
    • The contents of the SIS reparse points are opaque to your backup and restore applications, ensuring that upgrades to the SIS internals will not require a change in the SIS API or your backup and restore applications that call SIS API functions. You need only recompile your application with a new version of the SIS DLL, named Sisbkup.dll.
    • Because SIS is implemented as a file system filter driver, it constantly tracks the connections between the SIS links and the backing files. When the files are backed up and restored, SIS backup ensures that only one instance of the backing file will be backed up and restored, regardless of the number of SIS links that point to it."

     

    Thanks
    Shane

    Thanks Shane.

     

    FYI...... I tried using the sisadmin.exe on a DPM server to work with SIS and it does not work. I would guess you cannot even use sisadmin.exe to work with SIS-Limited.


    My Blog | www.buchatech.com | www.dpm2010.com
    Wednesday, October 26, 2011 2:08 PM
    Moderator
  • I've seen those pages, too. Like I said, I know what SIS is. And I still don't know what SIS-Limited is. There's no sisadmin.exe, etc.
    Wednesday, October 26, 2011 2:52 PM
  • Hello,

    Although I can't find any documentation to direct you to that differentiates the two, it's my understanding that it's a stripped down version of SIS to allow programs like DPM to enable SIS on a volume. 

    Is there a problem that you are running into?


    Thanks,
    Shane

    Thursday, October 27, 2011 12:02 PM
    • and the real deal: I copied the same file with different names to a replica volume, and they both consumed the equal amount of space
    I can accept that it's installed by confirming there's a registry key, but what does it do? Does it do anything at all?

    Hi Shane,

    Going back to Fejesjoco's question "see quote" How can one tell is the SIS-Limited is actually working?


    My Blog | www.buchatech.com | www.dpm2010.com
    Friday, October 28, 2011 2:27 AM
    Moderator
  • Hello,

    Other than the operation of DPM I do not have an answer for you on that question.  I can see if I can find out. It may take a while, if I find out anything for certain I will post it here.



    Thanks,
    Shane

    Friday, October 28, 2011 8:35 PM
  • Thanks for your help Shane!
    My Blog | www.buchatech.com | www.dpm2010.com
    Friday, October 28, 2011 8:37 PM
    Moderator
  • I am going through installing DPM 2010 on a WSS 2008 R2 server that we just purchased and was also wondering what the main difference is pertaining to installing the "sis-limited" version of SIS versus using the SIS that comes with SS. My main concern is because I can't enable SIS on a system or boot volume within SS without installing via the "sis-limited" route, would it be best to create a separate volume with SIS enabled via SS strictly for installing DPM and then another for the data just to avoid enabling "sis-limited" on the boot volume? If I enable "sis-limited" on the boot volume but then also turn on SIS within SS for where the backups will reside, what version of SIS will actually be controlling the deduplication process? I would imagine DPM would control any SIS related processing using the "sis-limited" version of SIS while the OS would control any volume where SIS was enabled within SS but because there is no documentation on this I am unsure on how to proceed.

    Thanks for any update on the differences between "sis-limited" and the version of SIS that comes with SS.


    -Adam
    Wednesday, December 21, 2011 9:03 PM
  • All,

    I have some new information regarding this after discussions with MS and a DPM MVP.

    The SIS-Limited is actually a SIS Filter driver. The SIS Filter driver is what runs on DPM. From what I know you wont be able to manage this like you can with full blown SIS.

    DPM enables the filter driver so it can properly handle SIS files on a protected server. For example you may have SIS running on an Exchange server and DPM will know how to handle the SIS data properly when protecting it by using the SIS filter driver. DPM does not use SIS to conserve space in the storage pool when running SIS-Limited, so there is no de-dup by SIS on your DPM storage pool in this setup.

    However there is a way to run a full SIS deployment on DPM, this is by installing DPM on Windows Storage Server. If you install DPM on a Windows Storage Server you'll be able to use SIS for all data you store in your storage pool. Here is the only article/documentation on installing DPM on Windows Storage Server: http://www.itexpertmag.com/server/turn-dpm-and-windows-storage-server-into-an-appliance .

     

    Links that show DPM is supported on Windows Storage Server:

    http://social.technet.microsoft.com/Forums/en-US/dpmsetup/thread/c2cf58c9-970a-45b2-bbe7-b096669f94e5/

    http://technet.microsoft.com/en-us/library/ff399021.aspx (Below in Community Content)


    My Blog | www.buchatech.com | www.dpm2010.com

    Friday, December 23, 2011 8:31 AM
    Moderator