Do you know if exists a write-once-read-many (aka: WORM) USB flash or SD memory?

I need an electronic write once memory to meet law requirements for storing sensitive data, and I want an alternative to my actual solution of CD-R discs.

I found that SanDisk produced some WORM SD card, but now this kind of card seems to be out of production.

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    Nobody knows any alternative to CD-R? – Tobia Feb 5 '16 at 18:42
  • greentec-usa.com/wp-content/uploads/2015/04/… for bigger data. i have found anything for smaller like you want. Im sure you could invent something to do the trick. – NetworkKingPin Feb 5 '16 at 19:03
  • Have you considered storing your data in a cloud? I'm sure you can find providers who can prove the upload date of your files and whether they have been changed since upload. – Máté Juhász Feb 6 '16 at 12:43
  • It is a good idea but the law requirement asks for a local copy of worm backup. – Tobia Feb 6 '16 at 16:41
  • @Tobia you may want to see if one of my previous answers to a similar question is something you'd be interested in. – Vinayak Feb 8 '16 at 6:48

Given that DVD/CD drives are now more often external and connected via USB, they do not conflict with your request for an alternative.

I agree that CD-R discs are not ideal, especially after having a couple go bad on me after a few years. But you could instead upgrade to the compatible M-DISC, where M stands for Millennium.

While I don't know if an M-Disc will really hold for a thousand years, or that anyone will care about your data at that time, M-Discs have become much cheaper in the last few years. For example on Amazon, Millenniata 4.7GB M-Disc Write Once and Read Forever, Read 16x/Write 4x Speed, 50 Pack goes today for $124.95. You can also today find Blu-ray M-Discs.

Millenniata 4.7GB 50 Pack

You would have to choose carefully your DVD/CD drive for compatibility with M-Discs. I have found this M-Disc's list of devices that can write, but I cannot vouch for its completeness.

If you wish to go up another notch, you could pass to WORM tape cartridges, but there you are multiplying the price-tag by a factor of 10.

SD WORM cards seem to have gone out of fashion, while Flash-using WORM seems not to exist. So as far as I can see, the options that are left are CD-R, M-Disc or tape.

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  • One big limit is that a CD/DVD has 99 tracks so after 99 writes I have to change it... This is my actual solution but I'm looking for alternatives. – Tobia Feb 6 '16 at 13:52
  • Is M-DISC blu-ray with 25GB enough? Amazon example. – harrymc Feb 6 '16 at 15:28
  • The problem is not the size ( I have to store only few KBs per day) the problem is how many session I can open. For example CD discs can have only 99 sessions. If I write 99 times 1MB I have only 99MB used but I cannot open another session. For Dvd is the same. – Tobia Feb 6 '16 at 15:31
  • This document says "more than 300 tracks can fit into the width of a single strand of hair on the Blu-ray Disc", which means a huge number of tracks. To be sure, and if you have access to a Blu-ray capable writer, you could invest in one ordinary Blu-ray disc to find out how many tracks/sessions it can hold - M-Disc will be the same. Otherwise, only tape is left, but it is costlier. – harrymc Feb 7 '16 at 13:15

For flash based memory I can't seem to find anything either. This talks about writing to the ones you're talking about but that doesn't get you any.

You could use a software to make a USB drive read-only like this one Softpedia download, but software is breakable and a fat32/64... system might not even recognize that there is security and go right through. The other recommendation would be to get one of the flash cards that has the lock switch, write your data, lock it, then break the toggle off... still, someone could probably switch it back with a paperclip or something.

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  • The switch on the side of memory cards (at least SD cards, maybe others) is a lot like the tabs on the bottom of a cassette tape. The switch on the side of the card simply tells the reader whether or not it is supposed to writeo, without actually changing anything electrically on the card. Modifying a reader to ignore that pin effectively makes every card inserted writable. – isaacparrot Mar 4 '18 at 3:12

Have you considered something like DLT, which has WORM media available?

DLT tapes have WORM media, but you might not have the option to add a DLT tape drive to the systems you're working on. You could probably find a DLT system that supports WORM for relatively little money these days, since LTO has mostly taken over for DLT.

It may also be worth noting that LTO has WORM media available as well, starting with LTO-3.

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  • I never tried DLT, do you think it is better/faster then burning a CD? – Tobia Feb 12 '16 at 7:30
  • It's certainly not going to be faster, as the tape needs to seek to the writable area, which gets further away from the beginning of the tape each time you write to it, and it needs to be rewound before it's ejected. That said, the time to do that is not obscene, and might be faster than it sounds. "Better" is a value judgement, I can't say whether it's better or not for your particular scenario, but I'd encourage you to investigate it. At very least, it's provably WORM, as opposed to flash-based methods. – NDC Feb 12 '16 at 21:18

There is a company that may provides the WORM Card like solution. This company is called Embestor. They provide customized service.

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    Welcome to Super User! Thanks for your contribution. Providing the link to the company's website would be a good improvement to this answer. – robinCTS Jul 6 '18 at 8:39

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