TFAT on an Mass Storage Device accessible SD-CARD

We have an issue with SD-Card corruption (we resolved a previous issue some while ago on this, but now have another one)!

We are considering TFAT again (there are pros and cons).

However one potentially significant issue with TFAT I can forsee is that we also make the SD-Card accessible from time to time as a Mass-Storage device via the USB device port on the T30, which can then be accessed by an external Windows PC.

However, when connected externally via USB, will the external PC “see” the drive as FAT only, and potentially damage the TFAT table, leading to problems?

Are you aware of the fixes with in the roadmap issue 18481 done in 2.0 beta 2? If you are using Image V1.4 it still could be that there are some rare corruptions, specially if you write form different threads to the same storage location.

TFAT mainly protects you from sudden power loss / power of the device during writing. If you see issues otherwise, please check again if you also see them if you are using image 2.0.

From my point of view reading from a TFAT device on a desktop machine should be fine. You may be will see some issues on a SD Card which was unexpected removed or had a power outage. In that case may be only one of the FAT tables will be updated and on the desktop you only read the first table.
Writing to a TFAT device may be could be an issue as both FAT tables get out of sync. To be honest we never made some deeper investigations on this.

Thanks that’s very useful.

Can you just clarify please - when the SD-Card is not physically mounted on the external PC, but “made available” as a USB mass storage device, via device port of T30, is that the same as if it was removed and put into an external PC (i.e. the PC “sees” it as FAT, even though it is still attached to the T30)?

@KCP: If you access the SD-Card over a USB mass storage device shared with your computer, the SD Card is access directly by WinCE. In this case there should not be any issue with TFAT, as WinCE can handle this.

Thanks …