Conference cookie::raid_software_for_openvms

339.0. "RAID ANALYZE reports FE errors which can't be repaired" by COOKIE::FROEHLIN (VMS...riding into the setting sun!) Thu May 29 1997 13:30

    
    Problem:
    --------
    RAID ANALYZE/ARRAY reports forced error flags set for very high block 
    numbers. 
    
    
    Analysis:
    ---------
    The  FE flags which are set are reported for an unused portion of the 
    container file.
    
    A sample RAID ANALYZE report:
    
    Forced Error Descriptor:
    
        Location[0]:     8373376
        Location[1]:     8371332
        FE flags 0 through 8370969 were CLEAR
        FE flags 8370970 through 8371304 were SET
        FE flags 8371305 through 8371331 were CLEAR
    %RAID-W-ANFE, software forced error flags detected
    
    RAID Container Member:
    
        Chunk Size:      120  \
        Chunks/MDU:      10    > a so called meta data unit or MDU
        PMD Segm. Size   1    /
        MDUs:            6970
    
    Not  all space in the container file covered by FE flags is used. The 
    used space can be calculated as:
    
          used space = MDUs * ( Chunk Size * Chunks/MDU + PMD Segm. Size)
             8370970 = 6970 * (   120    *     10     + 1 ) 
    
    Some  more  explanations: A spare disk has ALL its FE flags set prior 
    of  being  used  in a RAID set. A reconstruct operation will write to 
    all  used  blocks  on  the  spare  disk used in a REPLACE command. In 
    pre-V2.4 the FE flags remain set for the unused portion at the end of 
    the container file causing the misleading error message.
    
    
    Workaround:
    -----------
    Replace  the  member  disk  with  the  above symptom under V2.4 which 
    clears the unused FE flag bits.
    
    A  special program (RAID$FE_CLEANOUT.EXE_{VAX,ALPHA}) is available to 
    clear these  flags  without  unbinding the array. Run the program and 
    specify the physical member device having the problem. 
    
    The program images can be copied from:
    
    	COOKIE""::AIM$PUBLIC:[RAID.V24.KIT]
    
    
    Solution:
    ---------
    A  future  version  of  the  product  will suppress the report of the 
    unused FE bits.