08-21-2023, 07:41 AM
(This post was last modified: 08-21-2023, 07:42 AM by BlueSky1958.)
Oscar cannot read card - card cannot be read by PC
Suspect that something became corrupted during a card eject, or a laptop reboot, or whatever. Regardless, my PC can no longer see any files on the card even though diagnostic says it has almost 343M of used space on it. Anyone know of a way to access it again? The card shows up in Windows Explorer, but all shows no files (but with the aforementioned 434 MB used space).
RE: Oscar cannot read card - card cannot be read by PC
FAT, as in FAT32, stands for File Allocation Table. This is a section on the device that stores the starting memory location and number of memory blocks for that particular data and a sanity check value. Think of it as the Yellow Pages of the device. If it is corrupted, the data may be there, but it doesn't have the all the necessary information to provide an accurate location to the data. This can be caused by a failing device or interrupting a data write sequence (i.e: ejecting the card while it is being written to).
Recovering the data requires special data reconstruction software, time, patience, and your favorite lucky charm to rebuild the table. There are professional services that can do this, but come at a very large cost. They are usually employed when the value of the data far outweighs all other considerations. Due to the very high cost of a professional service, makes it unfeasible for this type of data. This leaves you with the do-it-yourself type of project.
If you have been backing up to a dedicated directory on your computer as we recommend, or to OSCAR, then you will only lose the data for the day or days in between the last backup and the next valid import. I would recommend that you first try formatting the card. After formatting, copy a text file to the card, and then see if you can open the file and read it. These steps will verify that the card was successful in being formatted, and can read and write data. After this test, you can delete the file from the card. Also, before removing the card from the computer, you need to select the "eject" or "unmount" feature (this term is dependent on the O/S you are using). Computers do not immediately write data to a device. Instead, they use a memory area (cache) that will store the data until it becomes full. It then writes this data as a block to the device, and then repeats this process until you close it. Using the "eject" or "unmount" command will flush the buffer (empty), write any remaining data to the device, and terminate (close) the connection.
Here are my recommendations. Since the release of the AS11, and now its firmware update, some "oddities" seem to have presented themselves that may alter how you approach its use. Allow at least an hour after you end the CPAP's use before removing the card. For the SD card, I would try reformatting the card, and if there is any doubt after that, just replace it with a new one.
- Red
RE: Oscar cannot read card - card cannot be read by PC
Bet it happened while ejecting the card. Not worth the trouble of effort for data recovery process. I was able to see the contents again when I used a portable card reader, so that seems ok, despite it not showing any graphs in OSCAR for last night. Will check again tomorrow and maybe everything will be back to normal.
RE: Oscar cannot read card - card cannot be read by PC
Most CPAPs retain the summary data for an extended period. If you insert a new card, it will write all the summary data it has in its memory to the card. It just will not have the detailed data.
- Red
