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Thread: Attunity MS-SQL CDC-SQLCDCLGR service - maintenance and cleanup of transient storage

  1. #1
    Hillel is offline Developer
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    MS-SQL CDC-SQLCDCLGR service - maintenance and cleanup of transient storage

    Attunity R & D Sep-2006

    Attunity MS-SQL CDC - SQLCDCLGR service - maintenance and cleanup of transient storage.

    In AIS V5000 - SQLCDCLGR is the run time component that takes care of the transient storage maintenance.

    The parameters for maintaining the transient storage are held at the transientStorage section of the SQLCDCLGR input file.
    While in command mode - following will display a brief explanation of each attribute:

    sqlcdclgr -p help.

    The relevant section in this regard is the following one, which is self explanatory:

    <transientStorage
    directory='{Directory where transient storage is maintained}'
    maxFileSize = '{Maximum bytes per individual transient storage unit}'
    totalSize = '{Total size limit for allocated transient storage}'
    lowThreshold = '{Target space ratio (% from totalsize) for cleanup utility}'/>
    highThreshold ='{Occupied space ratio (% from totalsize) for launching cleanup utility}'/>

    Following defaults are assumed:

    <transientStorage directory='?xxx?'
    maxFileSize='1000000'
    totalSize='100000000'
    lowThreshold='65' highThreshold='85'/>

    As LGR service starts, it first checks for the existence of the specified working folder.
    If it is not there it creates it.

    Next – as logged data is written - it periodically keeps track of total size occupied by that folder.
    Whenever this figure exceeds the allocated size threshold – cleanup is launched.

    Cleanup is a synchronized operation.
    The actual point of checking cleanup condition and launching is as End_Of_File is detected.
    LGR would not stop its critical mission for maintenance purposes.
    This may result marginal deviations from the pre-allocated figures which are fixed right after that.

    Let's assume that the above default setting is taken.
    After a while - as a LOG scan ends - LGR detects that transient storage folder now occupies 90MB.

    Since it exceeds the volume imposed by the 'highThreshold'figure (which computes to 100MB X 85% = 85MB), Cleanup is launched.
    Cleanup will start removing allocated files in a sequential manner, namely old files first.
    It will keep on removing files until the folder size equals (or less than) the size computed by 'lowThreshold' figure.
    In this particular example the cleanup target is 65MB.
    This ‘cutting the tail’ logic preserves the continuity and the order of the remaining data.

    Note that storage units are files not records.
    Allocation and removal of temporary storage data is carried out in units of FILES.

    Configuration and tuning of transient storage figures as induced by application consideration will be discussed in a future post.
    Last edited by Admin_attu; 09-21-2006 at 03:47 PM.
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  2. #2
    obama5493 is offline Junior Member
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    Quote Originally Posted by Hillel View Post
    Attunity R & D Sep-2006

    Attunity MS-SQL CDC - SQLCDCLGR service - maintenance and cleanup of transient storage.

    In AIS V5000 - SQLCDCLGR is the run time component that takes care of the transient storage maintenance.

    The parameters for maintaining the transient storage are held at the transientStorage section of the SQLCDCLGR input file.
    While in command mode - following will display a brief explanation of each attribute:

    sqlcdclgr -p help.

    The relevant section in this regard is the following one, which is self explanatory:

    <transientStorage
    directory='{Directory where transient storage is maintained}'
    maxFileSize = '{Maximum bytes per individual transient storage unit}'
    totalSize = '{Total size limit for allocated transient storage}'
    lowThreshold = '{Target space ratio (% from totalsize) for cleanup utility}'/>
    highThreshold ='{Occupied space ratio (% from totalsize) for launching cleanup utility}'/>

    Following defaults are assumed:

    <transientStorage directory='?xxx?'
    maxFileSize='1000000'
    totalSize='100000000'
    lowThreshold='65' highThreshold='85'/>

    As LGR service starts, it first checks for the existence of the specified working folder.
    If it is not there it creates it.

    Next – as logged data is written - it periodically keeps track of total size occupied by that folder.
    Whenever this figure exceeds the allocated size threshold – cleanup is launched.

    Cleanup is a synchronized operation.
    The actual point of checking cleanup condition and launching is as End_Of_File is detected.
    LGR would not stop its critical mission for maintenance purposes.
    This may result marginal deviations from the pre-allocated figures which are fixed right after that.

    Let's assume that the above default setting is taken.
    After a while - as a LOG scan ends - LGR detects that transient storage folder now occupies 90MB.

    Since it exceeds the volume imposed by the 'highThreshold'figure (which computes to 100MB X 85% = 85MB), Cleanup is launched.
    Cleanup will start removing allocated files in a sequential manner, namely old files first.
    It will keep on removing files until the folder size equals (or less than) the size computed by 'lowThreshold' figure.
    In this particular example the cleanup target is 65MB.
    This ‘cutting the tail’ logic preserves the continuity and the order of the remaining data.

    Note that storage units are files not records.
    Allocation and removal of temporary storage data is carried out in units of FILES.

    Configuration and tuning of transient storage figures as induced by application consideration will be discussed in a future post.
    Thanks foir sharing.It's great



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