SD Card Lock/Unlock: A Mnemonic Device

As those who use Sleepyhead know, you sneakernet the SD card from your Machine to your computer. Sleepyhead is very good about warning you to lock (write protect) your SD card before putting it into your computer's SD card reader, lest your data be inadvertently overwritten. You do that by sliding the little tab on the side of your SD card. So far, so good.

But traveling either between the machine and the computer, or the computer or the machine, you may forget which tab position is locked and which is unlocked, as happened to me. Some SD cards clearly label "locked" and "unlocked," but others, like the Respironics rebranded Lexar SD card that came with my Dreamstation do not, so it can happen that you forget which is which.

An easy mnemonic device is the tab is moved forward closer to the SD card's contacts for the unlocked (or write-enabled) position, which is where you want it to be when in your machine, but the tab is pulled back away from the contacts in the locked (or write-protect) position, where it should be when inserting it into your computer. Do check if your card might be labeled, though, since that's the best way to be sure.

I'm sure most people already know this, but if it can help prevent even a few from losing all their data, or even save someone from a needlessly frustrating "senior moment ," I hope it can help.

I think some machines store the data in the machine to prevent data loss. Not sure because mine uses a Smart card, and it's Smart! Jim

The warning to lock the SD card has nothing to do with accidentally overwriting the contents of the SD card.
Instead it was put in there back when the ResMed S9 machine was a commonly used machine because the S9 model machines are the only ones that care what is on the SD card.

Some Macs...and some Windows PCs (usually 8.xxx & higher) would put a little text file on the SD card and the S9 model machines didn't like having that extra file on the SD card and would then give us the "invalid card" message.
Respironics machines never cared...you could have a video on the card and Respironics machines wouldn't care.

The latest AirSense/AirCurve 10 model machines....they don't care if there is another file or not on the SD card.
I don't lock my SD card...and my Windows 10 computer puts that little text file on the SD card and the AirSense/AirCurve machines don't care and neither do I. I don't get the invalid card message (which BTW there is a way to remove the offending file if you forget and your S9 squawks) and I don't worry about remembering to do anything with the lock slider thing.

If a person isn't using one of the S9 models....doesn't matter if that little text file gets put on the SD card.

SleepyHead doesn't/can't write anything at all to the SD card.

Hurts nothing to lock the card though but it isn't the end of the world if you don't.

Actually, Pugsy is right. I just threw caution into the wind and inserted my SD card unlocked. Not only didn't Windows (on Vista, believe it or not) write anything to the card (even hidden/system files), but when I reinserted the card into my Respironics Dreamstation, there was no apparent problem.

OK, so Sleepyhead's dire warning need not necessarily be heeded by users of more recent machines. Good to know, thanks.

If you have a Respironics Dreamstation, the solution is simple: keep the card locked all the time!

My Dreamstation (purchased in April 2017) happily writes to the Lexar SD card that came with it regardless of the position of the lock tab. Maybe older machines care, mine doesn't. I figured this out by accident, since I was always screwing it up.

This is not a violation of the SD specification. The write-protect feature is optional. Here's a link, or at least as close to a link as I can do since I'm not registered: https: //en. wikipedia. org/wiki/Secure_Digital

SnoringInOregon wrote:If you have a Respironics Dreamstation, the solution is simple: keep the card locked all the time!

My Dreamstation (purchased in April 2017) happily writes to the Lexar SD card that came with it regardless of the position of the lock tab. Maybe older machines care, mine doesn't. I figured this out by accident, since I was always screwing it up.

This is not a violation of the SD specification. The write-protect feature is optional. Here's a link, or at least as close to a link as I can do since I'm not registered: https: //en. wikipedia. org/wiki/Secure_Digital

You're right. It seems devices can adhere to the write protect or not. It seems our machines do not.

The presence of a notch, and the presence and position of a tab, have no effect on the SD card's operation. A host device that supports write protection should refuse to write to an SD card that is designated read-only in this way. Some host devices do not support write protection, which is an optional feature of the SD specification. Drivers and devices that do obey a read-only indication may give the user a way to override it.

https://en.wikipedia.org/wiki/Secure_Di ... d_security

So it seems Sleepyhead's dire warnings need not necessarily be heeded after all for most recent machines.

xxyzx wrote:

Sheepish wrote:Actually, Pugsy is right. I just threw caution into the wind and inserted my SD card unlocked. Not only didn't Windows (on Vista, believe it or not) write anything to the card (even hidden/system files), but when I reinserted the card into my Respironics Dreamstation, there was no apparent problem.

OK, so Sleepyhead's dire warning need not necessarily be heeded by users of more recent machines. Good to know, thanks.

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the problem started with win8
vista was not a problem with writing extra files on a card

Pugsy explained it, it was with Resmeds not Respironics, don't think it had anything to do with Windows, but Resmeds when using macs. Then it just became a generic warning for everyone using Sleepyhead, so SH wouldn't get blamed for causing the problem. You can always just let the cpap erase the data on the card as it will re-write the data it has in cpap memory back on the card.

don't think it had anything to do with Windows, but Resmeds when using macs.

I don't have a Mac but I have had several Windows versions over the years with my S9 machines.
Windows 8.xxx or higher would definitely put that little text file on the SD card and my S9 would complain and I would get the invalid card message.
I often forgot to lock the card because for years I had used either Vista or Windows 7 and the S9 never complained so I would often forget to lock the card.
After I upgraded Windows to the offending versions I got quite adept at manually removing that annoying little text file.
Now that I am using the AirSense/AirCurve model....I don't bother locking the SD card.

Only the S9 cares about what is on the SD card.

SnoringInOregon wrote:If you have a Respironics Dreamstation, the solution is simple: keep the card locked all the time!

The solution is even simpler... IT DOESN'T MATTER ONE WAY OR THE OTHER TO THE DREAMSTATION.

The problem existed only on early S9 models. NO other CPAP models were affected. Listen to Pugsy not alphabet boy.