Omnis Technical Note TNDF0001

Checking Data Files

There has been occasional reports of problems with OMNIS data files due to caching; certainly any caching at the workstation level is liable to cause problems.

Generally one might expect a busy transaction based application with many users to experience minor datafile damage every few days or few weeks. This is a measure of the reliability of the technology employed, with peer-to-peer sharing it only needs one workstation or part of the network to have a problem and the datafile is likely to get damaged (and mirroring of the datafile is no help here).

Fortunately nearly all damage is completely transparent to the user and Omnis is quite able to work around it with no loss of data. This is what 'Quick check' does, it reports problems which have earlier been encountered in normal operation which have been successfully circumvented but which eventually should be repaired (if they hadn't been circumvented an error would have been reported at the time). Sometimes 'Quick check' reports problems which don't exist, some sort of temporary network glitch causes a problem to be flagged and 'Quick check' remembers it and reports it as a damaged datafile.

The following advice is suggested to any customer who is frequently checking a datafile and finding problems but experiencing no actual loss of data:

1)
If there are any doubts make sure local caching is switched off and check the network, network cards, etc.
2)
Make sure there is always plenty of free space in the datafile.
3)
Arrange to have downtime every few months (two months for a busy datafile, six months
for less busy) to do a complete repair run on the datafile. Select all the files, switch on all the options including 'Perform repairs' and let it run. If there is time repeat this a second time.
4)
If this is done there is no need to repair the data every time 'Quick check' reports a problem. Remember that Omnis is fussy, most of the items shown in the check data log are not serious.