memtech flashdrives

How often do you write to the drive? We only write during boot and shutdown on our flash drives. We never have much problem as you described. Do your customers happen to turn off power while writing to the drives?

I must confess we use the Windoze 2K OS and so the drive is used by both the OS for swapping and by the application.

We do not know how much write the customer application perform per second.

The problems we have met, particularly for the vibration tests during the qualification were found with new drives and a low amount of disk writes.

I don't think the problem comes from overwriting the same memory location too many times, thus exceeding the limited number of cycles for the flash, since the problems often appear at the beginning of the tests when only few write access have been made.

We also suspect problems perhaps with power supply spikes or ribbon cable twists that could occur due to vibrations.

I have read somewhere that flashdrives were considered not very reliable and that a defect rate of 10% was announced. I don't remember where this was written and for what operational conditions that was claimed.

This will definitely kill the flash drive, it's just a matter of weeks (perhaps months).

It doesn't matter. The OS is bad enough for the drive.

They must have poor solder joints. Actually, very poor joints that can be loosen with vibration. Most electronics (include Compact Flash, as we use in ours) can sustain 10G or greater shocks.

Try placing some large caps on the power line near the drive.

They are very reliable if you use them properly. Namely, run in read-only mode and write for occasional updates. Flash manufacturers do not recommend using them as read/write drives. Unfortunately, resellers (memtech?) don't follow the guide lines in pushing sales.

You are certainly right about the OS, but unfortunately, this is a request from our customer. We could perhaps try using a ramdisk for the swap but we have just replaced magnetic drives with these ones and of course, there was no problem with those, except during vibrations, that's why.

Agreed. We are now looking at Windoze XP embedded which includes a filter that prevent write access to the drives. That will perhaps solve our problems, provided the customer will accept to upgrade its application.

most interesting

We will try that, thanks

We should be able to do this thanks to the file filter in XP embedded

Have you looked at the Hitachi EnduraStar range? These are 20 or 30GB ruggedised 2 1/2" drives, designed for automotive applications.

Rob

Operating Vibration (sine wave) 1.0 G (22-500Hz) Non-operating Vibration (sine wave) 5.0G (22-500Hz)

If you hit a pot hole, there can easily be more than 1G force. Fortunately, no auto maker would use hard disk for mission critical part. Or, do they?

A kick in the device by a footballer (soccer) is much more than 40G

They sometimes connect radiosets on the same fieldbus as safety devices, such as speed regulators, about which we have heard some interesting stories, here, recently;)

A pot hole would cause a vibration for temporary loss of data. CF:15G, HD:1G

A ball hit would cause a shock for permanent damage. CF:1,000G HD:250G

For more comparative data between Compact Flash Drive and Hard Drive: