Is it ok to use a computer for critical operations ??

[ba]

hello.....

I would like to use a computer, having windows XP, for some critical job. The job demands that the PC be in operation for 24x7 hours. There will not be much user operation, and only one VB application will be in operation. The user will not be able to access hard disks or use the CD ROM drive.

All the necessary support like proper temperature control, continous power supply will be provided for.

My question is , will this system be reliable, also what are the chances of the PC hanging up ??

I think the main reason for a PC to hang up is that there may be several programs running at the same time.

Any opinions ??

bye bye

[Ttelmah]

Almost certainly not a good idea.
A lot will depend on how 'critical' the application is, and the timescales involved. For _really_ critical applications, where responses must be guaranteed at short timescales, you need to be considering very different hardware/software indeed (you may even need to be using a processor, which is certified as having no unknown states, and a programming language with similar certification - read _expensive_). However provided a 'pause' my be acceptable, the answer is to use an 'industrial PC', rather than a conventional computer. The big 'key' change on this, is that it will have a hardware watchdog. Then combine this with a less bloated OS, than normal XP (XP 'embedded' - this allows you to remove individual components from the OS, and build a kernel, only containing the parts that are needed, and none of the automation 'dross', with the increased risks this brings). If you ensure that in the event of a pause in the operation, the watchdog will activate, that the delay for this to restart the machine is acceptable, and that during the restart, the controls will not go into any unsafe state, you then have a potentially 24/7 machine. If you go with the kernel running entirely in RAM, and having no 'swap', you may be able to use a 'flash' drive, instead of a hard drive, with a great increase in reliability.
I doubt if VB, will be considered an acceptable language for any intrinsically critical enviroment though.
Using such enviroments under WNT embedded, and later W2K embedded (so far we have avoided XP embedded, since it is uncomfortably large on the flash drives), I have systems that have been in use continuously for over 5 years, with non stop control and monitoring.

Best Wishes

[asmallri]

[MikeValencia]

I've worked at a router startup company back in 2000 that used Windows NT instead of an RTOS (they later used VxWorks and Embedded Linux in later projects).

I've also seen a McDonald's drive-thru ordering menu screen do a "blue-screen" and saw it was Windows NT running on it.

I also know of credit card processing centers consisting of farms of Unix machines.

You can't really have a '24x7' 100% uptime system; something's bound to take it down. just make sure that you can recover within minutes. For example, a "5-Nines" system, which many telecom companies try to strive for, means that the system be operational 99.999% of the time. That means, they are only allowed up to 5 minutes of downtime each year.

[asmallri]