This happens to me on a regular basis (once a month or so between 200+
systems).
Normally when I have seen it, it is when the system gets rebooted by
abnormal means (button on front or blue screen or similar). Once in a
blue moon it will happen on a very active large file but I cannot track
that one down to heavy writing or JRFS as the file involved is a JRFS
written file.
Richard Kann
Comp-Ware Systems, Inc.
On 4/26/2011 4:12 PM, Simon Verona wrote:
Jim
I mean physically corrupt...
If you do a COUNT [Filename] you crash out with a "Readnext error
2007, file is corrupt message" (or similar).
JCHECK with no options confirms the corruption (I double check by
running it multiple times).
To correct, I have to run JCHECK -MS [Filename] with all users logged out.
Typically, the files that this happens to are high activity files,
with lots of smallish records in. I suspected that the size maybe
was the issue so I converted one of the customers into a multipart
file but within a month one of the parts has corrupted.
The file is normally discovered as corrupt when reading a record
(either atomically, or when running a report).
The problem is that it's not a completely random event - whilst I
can't predict when and where it's going to happen - I notice that some
systems are more prone to the error and that certain files are more
likely than others to have the problem.
I've kind of eliminated multi-user writing as being a cause - one of
the files is only written to by a single program - this sets an
execution lock to ensure that only one process can update the file at
a time. It is ironically, this file that statistically corrupts the
most often.
I'm sorry if I'm a little vague about the issue, but I don't really
have a grip as to what is going on. I don't know *when* the files
are corrupting - only that they _are _ corrupt.
Regards
Simon
-----Original Message-----
From: Jim Idle <[email protected]>
To: [email protected]
Date: Tue, 26 Apr 2011 12:50:26 -0700
Subject: RE: File Corruption... Causes?
Do you mean logically corrupt (your records are wrong) or
physically corrupt (you have to use jcheck)? You cannot physically
corrupt a file by writing to it without taking a lock, you will
just get trash results in your file. When are you discovering the
data is corrupt? There are lots of things that you can do to
actually corrupt it and some things (such as running jcheck when
people are writing to the file) that might make you think it is
corrupt.
Jim
*From:*[email protected] <mailto:[email protected]>
[mailto:[email protected] <mailto:[email protected]>]
*On Behalf Of *Simon Verona
*Sent:* Tuesday, April 26, 2011 12:39 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* File Corruption... Causes?
This issue is generic, and relates to a number of similar jBASE
3.4.10 based systems running Windows Server 2003.
We have an ongoing issue with file corruptions in j4 format files.
The problem appears somehow to be application driven - I suspect
this because across a number of systems, the files that corrupt
are always the same ones...
So, I'm looking for inspiration at an application level as to what
could cause file corruptions.
One thought I had was a WRITE without previously doing a
READU. I've not managed to duplicate the issue doing this, but
it's difficult to simulate a multi-user test that replicates what
the application might be doing.
Does anybody know if this *could* be the cause, or know of some
other application (data-basic) issue that could cause a J4 file to
be corrupted?
thanks in advance
Simon Verona
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