I need to delete the removable bit property on a SDHC flash memory card, this in order to make a SD flash memory card a fixed disk drive in an embedded application. I have 2 partitions one for windows and 3rd parity software packages, and another is for the application and historical data. My problem is that after a Windows boot only one partition is accessible (C: drive) the 2nd partition (D rive) I have to manually assign a letter to make it accessible, but it must be an unattended application.
Reason of still using Windows-NT SP6a is due to driver and hardware compatibility of excising Siemens ISA communication cards to PLCs expensive to replace.
Are there solutions to address this issue using SDHC flash MMC?
I use Compact Flash (CF) memory cards before they work fine as a fixed disk but they are more expensive and they are almost obsolete.
The Fixed vs Removable bit is answered by the card's firmware when the host controller asks it on Windows' instructions. The only way I know would be to modify the card's firmware, and I've heard about it for on type of CF card only.
Most P-Ata Raid host controllers answer "Fixed" even if you Raid consists of removable CF cards, like the good A-Data 266x. Maybe some SD adapter do it as well?
I didn't check if fixed SD cards exist. Some CF are fixed, which is praised when installing an OS.
Replace CF by SD: I don't know any SD as fast as a good CF, especially for writing small files. I consider it a huge drawback. Check the random 4kB writes with CrystalDiskMark (or the more complicated IOMeter). With new models arriving, I don't consider CF obsolete.
Several volumes on a removable disk: this is accepted by W95b, WMe, Nt4.0 sp0 but NOT by Nt4.0sp6a nor W2kSp4, both removing the extra volumes. You will lose the extra volumes each time you connect the CF to a Usb reader for instance. Xp is worse as it doesn't install willingly on a removable media.
So to me, the most prudent way would be to have one volume only if you can (add an extra flash card?) and stay at fixed CF.
December 10, 2009 1:44:48 PM
Dunno if this is still an issue or not, but is there a DiskPart utility under NT4? If so, you might be able to use autoexnt.bat to script it to automatically mount the second partition when Windows boots.
I found this thread today while looking for something else (I need to make a fixed disk show as a removable disk), and thought DiskPart might do the trick for you.
Sorry for delaying my reply, I did not notice your response.
As a fact I am using CF cards with 2 partitions on it and they work very well, but my customer think that CF cards are almost obsolete, harder to find and a lot more expensive than SD cards, besides that CF cards work very well but the fast 300X and up CF cards are too expensive. The fastest SD card I tested is about a 266X CF card but maybe in the near future SD cards will be as fast as CF cards.
Thanks and Regards