reconciling disk consumption

Last post 09-21-2020, 3:20 AM by Wwong. 3 replies.
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  • reconciling disk consumption
    Posted: 09-01-2020, 8:37 PM

    Hi,

    I have a test Linux MA using a local filesystem directory as a library.

    All is working so I can complete my tests however I do not understand the library consumption figures.

     

    Linux lv_root -> size = 55g, available = 34G

    (library is /backup which is not a separate lv)

     

    Local library reports -> capacity = 54.5GB, free space = 33.17GB

    This matches Linux well

     

    The mount path within the library reports -> same free space and capacity plus ....

    total app size = 14.26GB.  This is right.  Cross-check by ...

           - add job sizes, incl metadata

           - view contents of media

           - du -sh /backup

           - these are all consistent

    size on disk = 36.77.  Whence comes this?  This is my question.

     

    If my library was a cloud library it could be possible that the size on disk number does not get updated

    ( Media Management Configuration -> Service Configuration -> Process volume size updates for cloud mount paths)

    but that does not apply here.

     

    Any thoughts?

    TIA

  • Re: reconciling disk consumption
    Posted: 09-14-2020, 7:55 PM

    Hi TIA

    Could you please provide a screenshot from the CommServe GUI as well as an output of the space on the filesystem.

    Just want to more details to wrap my head around your issue.

    Technically CommServe uses a "check space interval - default is 30 minutes" which polls the MediaAgent to collect details on the space consumption. This is then reported back to the CommServe and stored/updated in the CSDB, before it is reflected in the CommServe GUI. 

    If there is a discrepancy, this could be either an issue with the Check Space or a problem with the CSDB not updating/reflecting the latest stats. 

    Kind Regards

    Winston 

  • Re: reconciling disk consumption
    Posted: 09-14-2020, 8:32 PM

    Thanks Winston.

    SInce I last looked at this, the numbers have come back into the realms of reasonable.

    I do notice the 30m refresh interval following an aging job or the deletion of backups.  It does take a little while to see the numbers adjust.

    But the "size on disk" did not adjust in my test environment - even after a day.

    However, today, the size on disk (26.65G) is within 2G of what Linux reports (29G -> du -sh /backup).  My guess is the 2G delta can be accounted for by meta-data.  Is that a plausible assumption?

    So, as the numbers are now reasonable, there is not much point adding screen shots but could there be two update processes happening here?

    Rgds

  • Re: reconciling disk consumption
    Posted: 09-21-2020, 3:20 AM

    Hi antechinus

    You are correct beside the check space interval there is also a volume size update parameter and that could explain why there is a discrepancy, as the volume size update does require the OS to physically verify the CHUNKs size to correctly report the consume space. 

    Furthermore, if the environment is busy (due to other operations across other MediaAgent), there could be a delay reporting back to the MediaManager on the CommServe, resulting in the slight size discrepancy being reported

    Regards

    Winston 

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