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Conference ulysse::rdb_vms_competition

Title:DEC Rdb against the World
Moderator:HERON::GODFRIND
Created:Fri Jun 12 1987
Last Modified:Thu Feb 23 1995
Last Successful Update:Fri Jun 06 1997
Number of topics:1348
Total number of notes:5438

634.0. "Does Ingres support Volume Shadowing?" by ODIXIE::RIDGWAY (Florida Native) Tue May 01 1990 21:31

    Does Ingres support volume shadowing???
    
    Thanks,
    
    Keith R>
T.RTitleUserPersonal
Name
DateLines
634.1YesFILTON::BIRCHIt's not a bug, it's a creatureWed May 02 1990 18:257
    Volume shadowing (if by that you mean the Digital product) is
    transparent to applications; therefore you may shadow an Ingres
    database, just as you may an Rdb database, RMS files, or any other
    software package. VS worries about disk blocks, not
    files/databases/other software structures.
    
    PDB
634.2Thanks, and "official" words about Ingres relationship?ODIXIE::RIDGWAYFlorida NativeWed May 02 1990 23:4014
    Thanks,
    
    I wasn't sure how I wanted to ask the question.....I seem to remember
    some type of competitive knock off about Ingres and Oracle not being
    able to take advantage of VS.
    
    Also, does anyone know the party line about what officially our
    relationship is with Ingres?  I am responding to an RFP that asks about
    our relationship with Ingres.  Any verbage that I can pass along in
    response to the customer would be appreciated.
    
    Thanks,
    
    Keith R>
634.3My 2 centsMAIL::DUNCANGGerry Duncan @KCO - DTN 452-3445Fri May 04 1990 00:1729
    There is a minor problem with Oracle V6 and volume shadowing but this
    only appears when we have a disk failure so I'm not sure you want to 
    bring this up.  I don't know if it has been fixed or not.
    Anyway, it goes like this.
    
    If you have a shadow set which contains an Oracle database file AND
    you MOUNT another disk into the set, VMS will initiate a shadow copy in
    order to make sure that both (or all three) disks will eventually be
    the same.  At the time the shadow copy is started, there is a brief
    period of time (2-3 seconds I think) were all members of the set are
    shown as not available (or something like that).  
    
    The problem we experienced was that IF Oracle was attempting to write
    to that shadow disk and received some sort of not ready/not available
    message, the Oracle code didn't trap the return code and retry and
    the writing process aborted.
    
    I'm sorry I can't remember all the details but I do remember going
    round 'n round with the cusomter and finally told them to buzz off and
    have Oracle fix their code.  As far as I know, the problem has not
    happened again.
    
    Anyway, from a logical point of view, Oracle and Ingres (and the rest)
    cannot avoid volume shadowing if it is being used.  Also, the term
    "taking advantage" really doesn't have much meaning since all
    readers of the DUS shadow disk will received the same advantage without
    doing anything special.
    
    -- gerry
634.4Gimme that Laser...gotta a Oracle to bust!DPDMAI::DAVISGBEscapee from New Hampshire...Tue May 08 1990 17:4013
    Except in the case of Oracle, which doesn't have code to handle this
    situation on VMS....but of course, they're portable....
    
    I spoke with a sales rep in California yesterday who told me about
    another DEC sales rep who's wife is a sales rep for ...guess who? the
    big O in California.  I can imagine the hidden agenda when I go in and
    try to convince him that Rdb is the best solution for his customer,
    when his wife is "partnering" with DEC so sell Oracle...
    
    C'est La Vie!
    
    Gil