Conference orarep::nomahs::dbms

2602.0. "Corruption that comes and goes" by ukvms3.uk.oracle.com::PJACKSON (Oracle UK Rdb Support) Thu Feb 27 1997 08:07

    A customer was getting a bugcheck from DBO/ANAL @ PIO$FETCH_RET. A
    DBO/DUMP of the page he was trying to fetch showed it to contain junk.
    Last night when they were shut down I dialled into their system to
    DBO/ALTER the page, but when I displayed it in DBO/ALTER it looked OK.
    I came out of alter and dumped the page again, getting the same junk as
    before, not what I was seeing with alter. I tried the DBO/ANAL and it
    still bugchecked. I went in with alter and it still looked OK. I
    changed 1 bit in the free space and the checksum. Now, dump show what I
    was seeing with alter. DBO/ANAL still bugchecked, but on a different
    page. Dump showed this page to contain junk, but alter showed it to be
    OK. I changed it, commited, and the changed it back again. Now
    everything saw it as OK.
    
    I guess that this was some kind of caching problem, though it had
    persisted for several days.
    
    They have DBMS 5.1-1, VMS 5.5-2, and shadowed disks. 
    
    Has anyone seen anything like this before?
    
    They will be replacing their VAX with an Alpha next month, so they
    aren't bothered about checking the hardware, or getting operating
    system patches.
    
    Peter