If they are corrupted after a hard reboot then your biggest suspect by a long way is that there was actually a process (perhaps orphaned/zombie, perhaps the user says everything is closed properly but it isn’t) that was running when you went to reboot and it/they are not getting closed in a neat way. You should develop a shutdown script that verifies that everyone is off the system and there are no jBASE processes around. You can use the sysinternals toolset to help with that – you want to try closing the processes in the cleanest way possible and hard reboot without stopping the processes may well kill the processes in a drastic way.
Of course if you mean that someone is turning off the system at the mains, then the more heavily used files are pretty much bound to be corrupt. Only switching to J3 secure files would prevent that and as you say, that is a lot slower if you want to lose as little data as possible. On the memory thing – it is worth running the memcheck on a system as part of general maintenance, but if this is the issue, it will affect the file when it is in memory and only afterwards when it is flushed to disk will the disk version reflect whatever the problem is. So flushing the files from memory would not help at all as it is the memory that is corrupted anyway. If there are no hardware faults, then I think you need to be looking at the general operations of the users such as whether they just switch things off without a proper shutdown, make sure they have UPS and so on. Also, it is high time that you moved on to jBASE 5 I think. The J5 files there should in theory avoid corruption issues, though they were not very good performance wise when I last tested them (ages ago now). Jim *From:* [email protected] [mailto:[email protected]] *On Behalf Of *Simon Verona *Sent:* Tuesday, April 26, 2011 10:21 PM *To:* [email protected] *Subject:* RE: File Corruption... Causes? Jim Thanks for the thought viz-a-viz memory. I had considered that as an issue - is it possible that because these are active files, that they tend to stick in memory for longer and therefore have more of a chance of getting corrupted (I know that a hard reboot will almost certainly corrupt these files!). Is there a way (with jbase 3.4.10/win2003) of forcing these files to be flushed to disk more regularly? I seem to recall the ability to configure a file in jbase so that it forces a physical disk write on update - though this would hamper performance somewhat! I will make backups of the files before fixing them and see if devsup can advise (they tend to be large 1GB+ files but will zip well). Regards Simon -----Original Message----- From: Jim Idle <[email protected]> To: [email protected] Date: Tue, 26 Apr 2011 13:47:48 -0700 Subject: RE: File Corruption... Causes? You need to examine hex dumps of the files and see what data is getting overwritten and with what other data. The other thing you should do is download the latest Memcheck CD image and run a complete memory check on the system. Most PCs do not use ECC memory and other than crashes or strange things happening you do not realize that there is a memory issue. However you may find that this is something like opening the file and editing it with notepad, or something silly like that. Anyway, you might need jBASE to help you with that but make copies of the corrupt files before ‘fixing’ them; then you can look for patterns in the corruption. The fact that they are high activity files, just means that they are the most likely to exhibit the problem. You should do the memcheck overnight as soon as possible though. Just get the customer to stick the CD in and reboot. Jim *From:* [email protected] [mailto:[email protected]] *On Behalf Of *Simon Verona *Sent:* Tuesday, April 26, 2011 1:13 PM *To:* [email protected] *Subject:* RE: File Corruption... Causes? 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]] *On Behalf Of *Simon Verona *Sent:* Tuesday, April 26, 2011 12:39 PM *To:* [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 -- Please read the posting guidelines at: http://groups.google.com/group/jBASE/web/Posting%20Guidelines IMPORTANT: Type T24: at the start of the subject line for questions specific to Globus/T24 To post, send email to [email protected] To unsubscribe, send email to [email protected] For more options, visit this group at http://groups.google.com/group/jBASE?hl=en -- Please read the posting guidelines at: http://groups.google.com/group/jBASE/web/Posting%20Guidelines IMPORTANT: Type T24: at the start of the subject line for questions specific to Globus/T24 To post, send email to [email protected] To unsubscribe, send email to [email protected] For more options, visit this group at http://groups.google.com/group/jBASE?hl=en -- Please read the posting guidelines at: http://groups.google.com/group/jBASE/web/Posting%20Guidelines IMPORTANT: Type T24: at the start of the subject line for questions specific to Globus/T24 To post, send email to [email protected] To unsubscribe, send email to [email protected] For more options, visit this group at http://groups.google.com/group/jBASE?hl=en -- Please read the posting guidelines at: http://groups.google.com/group/jBASE/web/Posting%20Guidelines IMPORTANT: Type T24: at the start of the subject line for questions specific to Globus/T24 To post, send email to [email protected] To unsubscribe, send email to [email protected] For more options, visit this group at http://groups.google.com/group/jBASE?hl=en
