Read-only card reader?

[Victor Engel]

Are there any card readers that are read-only? I ask because it appears that on Macs, it's not really possible to prevent the OS from indexing cards unless you flip the switch to be read-only. Yes, you can set it not to index after it's mounted, but by that time, it's already done its damage. I've encountered situations where the card apparently is getting corrupted by this process. For now my solution is to change the card to read-only with the switch, but what if I forget?
Or maybe I can set the existing card reader to be read-only. Is there a way to do that? I can't think of any reason I would need to write to an SD card on the Mac. And I never need them to be indexed.

Seems like it should be simple: just ground the write-protect pin. Or maybe not. I see lots of posts for resolving an issue where the SD card is read-only so that it's writable again. I want the reverse. Most of the solutions out there are nullified when the card gets formatted in the device - in this case, an audio recorder.

--

Victor Engel

 

[John Vickers]

Are there any card readers that are read-only? I ask because it appears that on Macs, it's not really possible to prevent the OS from indexing cards unless you flip the switch to be read-only. Yes, you can set it not to index after it's mounted, but by that time, it's already done its damage. I've encountered situations where the card apparently is getting corrupted by this process. For now my solution is to change the card to read-only with the switch, but what if I forget?
Or maybe I can set the existing card reader to be read-only. Is there a way to do that? I can't think of any reason I would need to write to an SD card on the Mac. And I never need them to be indexed.

Seems like it should be simple: just ground the write-protect pin. Or maybe not. I see lots of posts for resolving an issue where the SD card is read-only so that it's writable again. I want the reverse. Most of the solutions out there are nullified when the card gets formatted in the device - in this case, an audio recorder.

I'm guessing that you are talking about SD cards.

The write-protect tab does not disable writes. Support for the write-protect tab is optional. The state of the write-protect tab is unknown to the circuitry inside the card. A host can simply ignore the state of the write-protect tab.

It would be possible to write host firmware that disabled writes - for example by modifying the firmware to always behave as if the card's write-protect tab was set to write-protect.

See:

Loading…

www.sdcard.org

Section 4.3.6 Write Protect Management

...

It is also possible to set internal write protection on the card, which is more robust than the write-protect tab.

This likely involves some low-level SD-card utility. I don't know how to do that on MacOS. If you have a microsoft box, this might help: https://superuser.com/questions/1580787/how-to-write-protect-sd-card

 

[Victor Engel]

Are there any card readers that are read-only? I ask because it appears that on Macs, it's not really possible to prevent the OS from indexing cards unless you flip the switch to be read-only. Yes, you can set it not to index after it's mounted, but by that time, it's already done its damage. I've encountered situations where the card apparently is getting corrupted by this process. For now my solution is to change the card to read-only with the switch, but what if I forget?
Or maybe I can set the existing card reader to be read-only. Is there a way to do that? I can't think of any reason I would need to write to an SD card on the Mac. And I never need them to be indexed.

Seems like it should be simple: just ground the write-protect pin. Or maybe not. I see lots of posts for resolving an issue where the SD card is read-only so that it's writable again. I want the reverse. Most of the solutions out there are nullified when the card gets formatted in the device - in this case, an audio recorder.

I'm guessing that you are talking about SD cards.

The write-protect tab does not disable writes. Support for the write-protect tab is optional.

Yes, I know that. That's one reason I'm looking for a reader that's not also a writer.

The state of the write-protect tab is unknown to the circuitry inside the card.

Not exactly. There's no direct method for the reader to sense the tab. There are protocols where the card can be asked for the status of write-protection The circuitry then returns a value using the protocol. But the software need not ask for this.

A host can simply ignore the state of the write-protect tab.

A host can simply decline from asking the card for the value of write-protection. The host cannot directly tell what the state of the write-protect tab is.

It would be possible to write host firmware that disabled writes - for example by modifying the firmware to always behave as if the card's write-protect tab was set to write-protect.

See:

https://www.sdcard.org/downloads/pl...ecificationVer9.10Fin_20231201.pdf&e=EN_SS9_1

Section 4.3.6 Write Protect Management

...

It is also possible to set internal write protection on the card, which is more robust than the write-protect tab.

This likely involves some low-level SD-card utility. I don't know how to do that on MacOS. If you have a microsoft box, this might help: https://superuser.com/questions/1580787/how-to-write-protect-sd-card

That doesn't help. I don't want to disable writes of the card. As soon as I put it back in the recorder, I want the recorder to be able to write to it. I want to disable writes by macOS only. I'm actually surprised there's no real way to do this in macOS.
Most of the websites that address this recommend to add the drive to the privacy section where you can disable indexing of drives. That doesn't work for two reasons:

• The OS adds indexing files the moment the card is inserted, and the card must be inserted in order to add it to the setting to disable indexing.
• The entry is removed when the card is ejected - it's not persistent. If it were persistent, this might be a solution.

Another solution online is to add a hidden file to the card stating to never index the card. That will only work until the card gets formatted in the device the next time.

P.S. My previous comment about grounding a pin doesn't work. I think what I was reading where that does work is for a different card. I don't have the link handy, and it's not relevant, so I'm disinclined to find it again.

--
Victor Engel

 

[TomV1]

Are there any card readers that are read-only? I ask because it appears that on Macs, it's not really possible to prevent the OS from indexing cards unless you flip the switch to be read-only. Yes, you can set it not to index after it's mounted, but by that time, it's already done its damage. I've encountered situations where the card apparently is getting corrupted by this process. For now my solution is to change the card to read-only with the switch, but what if I forget?
Or maybe I can set the existing card reader to be read-only. Is there a way to do that? I can't think of any reason I would need to write to an SD card on the Mac. And I never need them to be indexed.

Seems like it should be simple: just ground the write-protect pin. Or maybe not. I see lots of posts for resolving an issue where the SD card is read-only so that it's writable again. I want the reverse. Most of the solutions out there are nullified when the card gets formatted in the device - in this case, an audio recorder.

What process are you refering to that corrupts your card?

You may not have a reason to write or index an SD on the Mac but that does not mean others think the same.

 

[Victor Engel]

Are there any card readers that are read-only? I ask because it appears that on Macs, it's not really possible to prevent the OS from indexing cards unless you flip the switch to be read-only. Yes, you can set it not to index after it's mounted, but by that time, it's already done its damage. I've encountered situations where the card apparently is getting corrupted by this process. For now my solution is to change the card to read-only with the switch, but what if I forget?
Or maybe I can set the existing card reader to be read-only. Is there a way to do that? I can't think of any reason I would need to write to an SD card on the Mac. And I never need them to be indexed.

Seems like it should be simple: just ground the write-protect pin. Or maybe not. I see lots of posts for resolving an issue where the SD card is read-only so that it's writable again. I want the reverse. Most of the solutions out there are nullified when the card gets formatted in the device - in this case, an audio recorder.

What process are you refering to that corrupts your card?

Inserting the card into the slot of the Macbook. You can tell that macOS indexes the card when you insert it because it adds all its indexing crap to it.

My evidence that this is causing the corruption is that files that were playable before being inserted are no longer playable after being inserted. I've not done enough tests to confirm this is what is happening. Instead, I replaced the card in case of some sort of incompatibility and changed my workflow to download files using a USB connection instead (very slow) or by inserting the card after flipping the lock switch. Since doing that, I haven't encountered any corruption since replacing the card, which is being returned, so I probably won't be able to do enough testing to confirm what is happening.

You may not have a reason to write or index an SD on the Mac but that does not mean others think the same.

Others do not have access to my Mac. So that doesn't matter.

 

[Victor Engel]

Hmmm - I think I was wrong about how it works. The reader itself has a feeler that senses the switch, and this informs the OS whether the card should be writable or not.

 

[John Vickers]

Hmmm - I think I was wrong about how it works. The reader itself has a feeler that senses the switch, and this informs the OS whether the card should be writable or not.

Quite.

Do you think that if MacOS regularly corrupts SD cards, this would not be widely complained about ?

Perhaps it would help to describe your problem on a MacOS forum. Like the "Mac Talk" forum on DPReview.

Can you disable indexing on external media?

...

If you superglue the microswitch that reads the write-protect tab on a USB reader in the protected position, that would do what you ask for. Vaguely modern USB-3 SD card readers are faster than UHS-II SD cards.

 

[Victor Engel]

Hmmm - I think I was wrong about how it works. The reader itself has a feeler that senses the switch, and this informs the OS whether the card should be writable or not.

Quite.

Do you think that if MacOS regularly corrupts SD cards, this would not be widely complained about ?

It's possibly an incompatibility with a certain card, which is being returned.

Perhaps it would help to describe your problem on a MacOS forum. Like the "Mac Talk" forum on DPReview.

Hmmm - sure.

Can you disable indexing on external media?

Only those that are attached, it seems. And the problem is that the very attaching is what triggers the indexing. I'll be gradually trying different things with my new card and monitoring if the issue happens again. If not, maybe the issue was just an incompatibility with the card I was using before.

 

[Fred Greaves]

So a few thoughts and troubleshooting steps...

1. Are you experiencing this with multiple cards or a single card?

2. Do you have the ability to try more than one card reader to see if the issue persists with a different reader?

3. Have you tried switching usb cables?

4. Can you successfully play the files if you put the card back into the audio recorder?

5. Do you have another Mac or PC that you can try downloading the files with to see if they are still corrupted?

It is not unheard of for a reader to go bad. Years ago I had a reader that had some sort of a short and it would mount the card, and then randomly unmount it while downloading which, of course, caused some images to be corrupt.

One thing that could cause the Mac to do this, in theory, is if you have some bad ram, it could be glitching out files when there are memory errors in reading and writing the files. You could also have a bad hard drive or SSD, but you probably wouldn't see the same error every time, and you would see freezes, and other glitches as well (same with bad RAM).

In my experience, the Mac causing it is unlikely and with more than 30 years of using Macs and being a photographer, I have never had the OS corrupt a card... it's always been caused by a bad reader, usb cable, or memory card that was on the verge of failing.

You might also want to try running Disk Utility and check the health of the offending SD card, also.

Your Mac is probably not the culprit, but it shouldn't be happening... hopefully you can identify the element that is introducing the corruption.

 

[Victor Engel]

So a few thoughts and troubleshooting steps...

1. Are you experiencing this with multiple cards or a single card?

One card, which is being returned.

2. Do you have the ability to try more than one card reader to see if the issue persists with a different reader?

The issue is with the built-in reader that comes with the Macbook. Could I use a separate card reader? Yes.

3. Have you tried switching usb cables?

There are no cables involved. This i the built-in card reader I'm talking about.

4. Can you successfully play the files if you put the card back into the audio recorder?

Nope. Whatever is happening is corrupting the files.

5. Do you have another Mac or PC that you can try downloading the files with to see if they are still corrupted?

Yes.

It is not unheard of for a reader to go bad. Years ago I had a reader that had some sort of a short and it would mount the card, and then randomly unmount it while downloading which, of course, caused some images to be corrupt.

One thing that could cause the Mac to do this, in theory, is if you have some bad ram, it could be glitching out files when there are memory errors in reading and writing the files. You could also have a bad hard drive or SSD, but you probably wouldn't see the same error every time, and you would see freezes, and other glitches as well (same with bad RAM).

In my experience, the Mac causing it is unlikely and with more than 30 years of using Macs and being a photographer, I have never had the OS corrupt a card... it's always been caused by a bad reader, usb cable, or memory card that was on the verge of failing.

You might also want to try running Disk Utility and check the health of the offending SD card, also.

Been there, done that, didn't elucidate anything.

Your Mac is probably not the culprit, but it shouldn't be happening... hopefully you can identify the element that is introducing the corruption.

It's also possible the card is not compatible with the device. The device documentation even states so, but doesn't list any devices guaranteed to be compatible, which is frustrating. Support emails suggest that high capacity cards (>64 GB) may have more frequent incidents.

 

[Ellis Vener]

So a few thoughts and troubleshooting steps...

1. Are you experiencing this with multiple cards or a single card?

One card, which is being returned.

2. Do you have the ability to try more than one card reader to see if the issue persists with a different reader?

The issue is with the built-in reader that comes with the Macbook. Could I use a separate card reader? Yes.

3. Have you tried switching usb cables?

There are no cables involved. This i the built-in card reader I'm talking about.

4. Can you successfully play the files if you put the card back into the audio recorder?

Nope. Whatever is happening is corrupting the files.

5. Do you have another Mac or PC that you can try downloading the files with to see if they are still corrupted?

Yes.

It is not unheard of for a reader to go bad. Years ago I had a reader that had some sort of a short and it would mount the card, and then randomly unmount it while downloading which, of course, caused some images to be corrupt.

One thing that could cause the Mac to do this, in theory, is if you have some bad ram, it could be glitching out files when there are memory errors in reading and writing the files. You could also have a bad hard drive or SSD, but you probably wouldn't see the same error every time, and you would see freezes, and other glitches as well (same with bad RAM).

In my experience, the Mac causing it is unlikely and with more than 30 years of using Macs and being a photographer, I have never had the OS corrupt a card... it's always been caused by a bad reader, usb cable, or memory card that was on the verge of failing.

You might also want to try running Disk Utility and check the health of the offending SD card, also.

Been there, done that, didn't elucidate anything.

Your Mac is probably not the culprit, but it shouldn't be happening... hopefully you can identify the element that is introducing the corruption.

It's also possible the card is not compatible with the device. The device documentation even states so, but doesn't list any devices guaranteed to be compatible, which is frustrating. Support emails suggest that high capacity cards (>64 GB) may have more frequent incidents.

 

[Victor Engel]

So a few thoughts and troubleshooting steps...

1. Are you experiencing this with multiple cards or a single card?

One card, which is being returned.

2. Do you have the ability to try more than one card reader to see if the issue persists with a different reader?

The issue is with the built-in reader that comes with the Macbook. Could I use a separate card reader? Yes.

3. Have you tried switching usb cables?

There are no cables involved. This i the built-in card reader I'm talking about.

4. Can you successfully play the files if you put the card back into the audio recorder?

Nope. Whatever is happening is corrupting the files.

5. Do you have another Mac or PC that you can try downloading the files with to see if they are still corrupted?

Yes.

It is not unheard of for a reader to go bad. Years ago I had a reader that had some sort of a short and it would mount the card, and then randomly unmount it while downloading which, of course, caused some images to be corrupt.

One thing that could cause the Mac to do this, in theory, is if you have some bad ram, it could be glitching out files when there are memory errors in reading and writing the files. You could also have a bad hard drive or SSD, but you probably wouldn't see the same error every time, and you would see freezes, and other glitches as well (same with bad RAM).

In my experience, the Mac causing it is unlikely and with more than 30 years of using Macs and being a photographer, I have never had the OS corrupt a card... it's always been caused by a bad reader, usb cable, or memory card that was on the verge of failing.

You might also want to try running Disk Utility and check the health of the offending SD card, also.

Been there, done that, didn't elucidate anything.

Your Mac is probably not the culprit, but it shouldn't be happening... hopefully you can identify the element that is introducing the corruption.

It's also possible the card is not compatible with the device. The device documentation even states so, but doesn't list any devices guaranteed to be compatible, which is frustrating. Support emails suggest that high capacity cards (>64 GB) may have more frequent incidents.

Would it be too much trouble to ask which make and model of media that you had this problem with?

Sandisk Extreme 256 GB V30 labeled with 180 MB/s

 

[Ellis Vener]

Thank you.

 

[moficera]

Most problems with memory cards in devices like your audio recorder result from the creation of the resource forks by macos that is a separate file on non-Mac filesystems. It basically creates an empty file with the same name but a dot as the first character that confuses other devices. To get rid of these resource forks there are resource fork cleaners you can drop the card onto before having it ejected.

Maybe thats the cause in your case as well.

 

[Victor Engel]

Most problems with memory cards in devices like your audio recorder result from the creation of the resource forks by macos that is a separate file on non-Mac filesystems. It basically creates an empty file with the same name but a dot as the first character that confuses other devices. To get rid of these resource forks there are resource fork cleaners you can drop the card onto before having it ejected.

Maybe thats the cause in your case as well.

That explanation doesn't fit the data. The corruption first is apparent to the Mac, not the recorder. A subsequent recording in the recorder might very well be OK. It appears that the Mac is creating the problem during the process of creating those files. Cleaning up those files after the damage is done removes those files, but what remains is corrupted. Anyway, that card is returned now, and the replacement card (a different type) doesn't seem to have the issue.

Just to summarize, here is the sequence:

• Insert card into recorder.
• Format the card in the recorder (required in order to create the needed folder structure the recorder uses).
• Record a clip.
• Play the clip in the recorder to confirm it recorded.
• Shut down the recorder.
• Eject the card.
• Insert the card into the Mac.
• Use Finder to copy the file.
• Open the file using Adobe Audition.

In the case of the card just returned, the file will not open, with a popup stating it is corrupted or something like that. Inserting the card back into the recorder to try to play it there results in a similar message by the recorder.

If the same steps are repeated, but the lock switch is slid first, there is no issue.

Anyway, that's what SEEMS to be the case. The corruption seemed to happen about 20-25% of the time, so I can't be sure. It wasn't worth sleuthing out exactly what was happening when I was able to just return the card. I was able to view the hidden files added by macOS, hence my belief that that's what caused the corruption.

The first time I encountered the issue, the file was just over 2 GB. I thought maybe it was related to the file size. But the issue happened again with smaller files.

 

[moficera]

Ok, that sounds more like a defective card where the write access reveals the problem. Glad to hear a different card works.

 

[John Vickers]

Most problems with memory cards in devices like your audio recorder result from the creation of the resource forks by macos that is a separate file on non-Mac filesystems. It basically creates an empty file with the same name but a dot as the first character that confuses other devices. To get rid of these resource forks there are resource fork cleaners you can drop the card onto before having it ejected.

Maybe thats the cause in your case as well.

That explanation doesn't fit the data. The corruption first is apparent to the Mac, not the recorder. A subsequent recording in the recorder might very well be OK. It appears that the Mac is creating the problem during the process of creating those files. Cleaning up those files after the damage is done removes those files, but what remains is corrupted. Anyway, that card is returned now, and the replacement card (a different type) doesn't seem to have the issue.

Just to summarize, here is the sequence:

• Insert card into recorder.
• Format the card in the recorder (required in order to create the needed folder structure the recorder uses).
• Record a clip.
• Play the clip in the recorder to confirm it recorded.
• Shut down the recorder.
• Eject the card.
• Insert the card into the Mac.
• Use Finder to copy the file.
• Open the file using Adobe Audition.

In the case of the card just returned, the file will not open, with a popup stating it is corrupted or something like that. Inserting the card back into the recorder to try to play it there results in a similar message by the recorder.

If the same steps are repeated, but the lock switch is slid first, there is no issue.

Anyway, that's what SEEMS to be the case. The corruption seemed to happen about 20-25% of the time, so I can't be sure. It wasn't worth sleuthing out exactly what was happening when I was able to just return the card. I was able to view the hidden files added by macOS, hence my belief that that's what caused the corruption.

The first time I encountered the issue, the file was just over 2 GB. I thought maybe it was related to the file size. But the issue happened again with smaller files.

Sounds a bit like the problem with Sandisk cards in the Canon R5M2.

Horshack might have some ideas. (He used to work on this stuff).

Maybe best to just avoid Sandisk now.

 

[Victor Engel]

Most problems with memory cards in devices like your audio recorder result from the creation of the resource forks by macos that is a separate file on non-Mac filesystems. It basically creates an empty file with the same name but a dot as the first character that confuses other devices. To get rid of these resource forks there are resource fork cleaners you can drop the card onto before having it ejected.

Maybe thats the cause in your case as well.

That explanation doesn't fit the data. The corruption first is apparent to the Mac, not the recorder. A subsequent recording in the recorder might very well be OK. It appears that the Mac is creating the problem during the process of creating those files. Cleaning up those files after the damage is done removes those files, but what remains is corrupted. Anyway, that card is returned now, and the replacement card (a different type) doesn't seem to have the issue.

Just to summarize, here is the sequence:

• Insert card into recorder.
• Format the card in the recorder (required in order to create the needed folder structure the recorder uses).
• Record a clip.
• Play the clip in the recorder to confirm it recorded.
• Shut down the recorder.
• Eject the card.
• Insert the card into the Mac.
• Use Finder to copy the file.
• Open the file using Adobe Audition.

In the case of the card just returned, the file will not open, with a popup stating it is corrupted or something like that. Inserting the card back into the recorder to try to play it there results in a similar message by the recorder.

If the same steps are repeated, but the lock switch is slid first, there is no issue.

Anyway, that's what SEEMS to be the case. The corruption seemed to happen about 20-25% of the time, so I can't be sure. It wasn't worth sleuthing out exactly what was happening when I was able to just return the card. I was able to view the hidden files added by macOS, hence my belief that that's what caused the corruption.

The first time I encountered the issue, the file was just over 2 GB. I thought maybe it was related to the file size. But the issue happened again with smaller files.

Sounds a bit like the problem with Sandisk cards in the Canon R5M2.

Horshack might have some ideas. (He used to work on this stuff).

Maybe best to just avoid Sandisk now.

Yeah, the returned card is not one of the ones on the list. It was a V30 card, and I think all the ones on the lists I've seen with problems were V60 or V90. It was nice being able to rely on SanDisk just based on the name. I won't be doing that anymore.

 

[Ellis Vener]

Most problems with memory cards in devices like your audio recorder result from the creation of the resource forks by macos that is a separate file on non-Mac filesystems. It basically creates an empty file with the same name but a dot as the first character that confuses other devices. To get rid of these resource forks there are resource fork cleaners you can drop the card onto before having it ejected.

Maybe thats the cause in your case as well.

That explanation doesn't fit the data. The corruption first is apparent to the Mac, not the recorder. A subsequent recording in the recorder might very well be OK. It appears that the Mac is creating the problem during the process of creating those files. Cleaning up those files after the damage is done removes those files, but what remains is corrupted. Anyway, that card is returned now, and the replacement card (a different type) doesn't seem to have the issue.

Just to summarize, here is the sequence:

• Insert card into recorder.
• Format the card in the recorder (required in order to create the needed folder structure the recorder uses).
• Record a clip.
• Play the clip in the recorder to confirm it recorded.
• Shut down the recorder.
• Eject the card.
• Insert the card into the Mac.
• Use Finder to copy the file.
• Open the file using Adobe Audition.

In the case of the card just returned, the file will not open, with a popup stating it is corrupted or something like that. Inserting the card back into the recorder to try to play it there results in a similar message by the recorder.

If the same steps are repeated, but the lock switch is slid first, there is no issue.

Anyway, that's what SEEMS to be the case. The corruption seemed to happen about 20-25% of the time, so I can't be sure. It wasn't worth sleuthing out exactly what was happening when I was able to just return the card. I was able to view the hidden files added by macOS, hence my belief that that's what caused the corruption.

The first time I encountered the issue, the file was just over 2 GB. I thought maybe it was related to the file size. But the issue happened again with smaller files.

Sounds a bit like the problem with Sandisk cards in the Canon R5M2.

Horshack might have some ideas. (He used to work on this stuff).

Maybe best to just avoid Sandisk now.

Yeah, the returned card is not one of the ones on the list. It was a V30 card, and I think all the ones on the lists I've seen with problems were V60 or V90. It was nice being able to rely on SanDisk just based on the name. I won't be doing that anymore.

 

[John Vickers]

Are there any card readers that are read-only?

Apparently so.

I just came across the Angelbird CFexpress and SDcard readers, and they have a write protect switch on the outside of the reader, intended to protect original recordings against inadvertent writes:

Loading…

www.angelbird.com

Loading…

manuals.plus

They're quite pricey, but they seem to do what you originally asked for.

I was interested because they seem to be necessary to update firmware on Angelbird CFexpress cards.