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Online backup of database with Alternate Buffer Pool is enabling LRU2 policy

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TitleOnline backup of database with Alternate Buffer Pool is enabling LRU2 policy
URL NameP188896
Article Number000140234
EnvironmentProduct: OpenEdge
Version: 10.2B, 11.x
OS: All Supported Operating Systems
Other: Database, PROBKUP, -B2
Question/Problem Description
Online PROBKUP results in enabling LRU2 policy being enabled.
PROMON, R&D, 2. Activity Displays, 3. Buffer Cache shows LRU2 replacement policy enabled.
Steps to Reproduce1. prodb sp2k sports2000
2. proutil sp2k -C enableB2 "Cust_Data"
3. proutil sp2k -C enableB2 "Cust_Index"
4. proserve sp2k -B2 100
5. mpro sp2k
FOR EACH customer NO-LOCK
END.
FIND FIRST _actbuffer WHERE _buffer-id = 3 NO-LOCK NO-ERROR.
DISPLAY
_Buffer-LRUEnabled
_Buffer-Active
_actbuffer._buffer-osrds
WITH FRAME fx SIDE-LABELS 1 COL.
Clarifying Information
Alternate Buffer pool enabled for Database objects.
Database startup parameter -B2 used to define Alternate Buffer Pool memory.
Error Message
Defect NumberDefect OE00208701 /PSC00234422
Enhancement Number
Cause
PROBKUP online reads all database blocks probkup needs to read into either the general buffer pool (-B) or the alternate buffer pool (-B2) as these database objects have been configured.  As such, online PROBKUP triggers the LRU2 enabled. Although backup does no LRUing, once the backup fills the alternate buffer pool the LRU2 mechanism kicks in for future access by other processes. In other words, if the sum of all the -B2 enabled data exceeds the value of -B2 setting, this will then initialise the LRU2 which defeats one of the aims of scoping the -B2 size. 
Resolution
Upgrade to OpenEdge 10.2B05 or 11.7.5, where online backup will restore the LRU2 enabled state if it was enabled during the backup.
Workaround
Use the -Bp option when issuing PROBKUP online, where the value of -Bp must be smaller than the value of -B2 for this workaround to be successful.
 
Example:
$  probkup online sports2000 sports2000.bkp -Bp 10
 
 
Notes
Last Modified Date2/3/2020 1:43 PM
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