Tech support 
Author Message
 Tech support

I have a case for the debate about tech support / Informix in general.
This was written a few months ago.

        I believe that every time I have called Informix support in the last
        year (except just now), I have spent 15 minutes or more on hold. The
        last time I asked a question, it was, "is the transaction log file
        [SE] written synchronously," which is of vital significance to us since
        if the answer is "no," we do not have dbase integrity in the event
        of a crash.

        I just talked to an engineer who read the case info to me:

        <case record>
        case # 126809
        isql 2.10.03B
        opened: 4/10/91
        closed: 9/18/91 by administrative default, i.e. it fell on the floor
        Wants to know if sync triggers code for transaction buffer write.
        Later: Wants specific proof of correctness of log writing.
        I was eventually referred to someone for authorization to receive
        the information on Informix internals.
        <end what I jotted of case record>

        Note that the 1st person I spoke to never understood the question,
        and the secrecy involved in disclosing whether their program is
        reliable (amounting to whether they open a file O_SYNC or not) is
        ludicrous.

        I am not sure that the person who read the case to me understood it
        either, although eventually he said he did and stopped repeating
        how a rollforward is done.

        I believe I tried a little further, but forget what happened exactly
        except that I never got an answer. Meanwhile, we found out from the
        kernel side that the transaction log wasn't written synchronously,
        and I also heard indirectly that Informix's response to that was
        that the transaction log was for transactions and not for dbase
        integrity across a crash, i.e. if you wanted transactions, you
        sacrificed dbase integrity. Our solution was to modify the kernel
        so that synchronous writing was forced somehow.

        The one time we got support that I was impressed by was right before
        the case I just discussed, when we had the big transaction rollforward
        nightmare; that was case #125978. They did go to extra lengths then;
        my only complaint there is that I believe the extra long time it
        took (~24 hours on a dedicated mainframe) probably results from a
        bad rollforward algorithm and I don't think they seemed interested in
        investigating it.

In the latter case we had to modify the binary to make it use extended
addressing in order to rollforward a single transaction; we monitored
the progress through the file via the kernel and found that performance
decayed exponentially, my guess is because of traversal of a growing
linked list for each element of the transaction.

The result of our experiences with Tech support was as Hogg has described:
all 4 of us who had to call (3 programmers and a production person) dreaded
the experience. After concluding in negotiations that Informix was not
committed to making their product reliable (our database cannot be corrupted)
we are replacing Informix in our project. Somehow in our dealings with other
vendors, we had built the expectation of more support than Informix was willing
to give. On the other hand, I have been impressed with the recent participation
in the board/list by Informix employees, since it gives me the impression that
there are responsible people there who understand the products' internals
and care about the products and the customers. Now if the business policies
would omit flat out refusal to make things work under a "support" agreement..

Bill Ross
Computer Sciences Corporation
NASA Ames Research Center



Thu, 13 Oct 1994 01:48:04 GMT
 
 [ 1 post ] 

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