From Newsgroup: comp.sys.acorn.hardware
Paul Stewart <
phorefaux@gmail.com> wrote:
Hi all,
Having recently suffered an MMC failure(thankfully not too drastic as MMC
as just gone into read only mode) I am looking for to hear from peoples experience with different storage mediums and adaptors.
For ease I have switched to another older and slightly slower MMC for the time being, but will be looking to replace with something else.
If you not guessed from my footer this will be for my A9home. This has
two internal 44 pin IDE interfaces, both of which can by quite picky as to what they will work with! My MMC adaptor approach has worked for many years, just wondering if I should stick with this approach or try
something else?
Currently I have a MMC adaptor connected to the 2nd interface via short cable(the interfaces being picky as they are, will not work when connected to the other interface!). Looking on Amazon and Ebay, I can see there are 44 pin IDE to SD adaptors and m.2 adaptors. Has anyone had success with using these type of adaptors?
Also is an SD card more robust then the MMC card when being used as the
main hdd? If the SD card were to fail, would it also go into read only mode, or just die a death? My failing MMC is a SanDisk Extreme Pro. I'm guessing will depend on the brand.
Any thoughts much appreciated.
For IDE to CompactFlash adapters, the protocol handling is in the CF card. ADFS/etc being slightly different from Windows, it can result in things
being picky about the brand of CF card.
For IDE to SD / MMC adapters, the adapter is doing protocol translation
between ATA and SD/MMC. So if the adapter works with one card there's a
good chance it'll work with another. However there are variations in the SD card protocol (notably the SD to SDHC change at 4GiB) which the adapter
would need to handle. Above 4GiB and below 2TiB I don't think there are any protocol changes (SDHC -> SDXC at 32GiB is a format change from FAT32 to
exFAT, but you'll be reformatting so it doesn't matter).
If you adapter is really for MMC rather than SD (from the megabytes not gigabytes era) then it might not support SD at all, or not SDHC, or some arbitrary size limit. Only thing is to try it.
For IDE to SATA adapters, one layer of protocol is being converted but
another is being passed through. I've had problems with them on an old
(~2004) laptop being picky about the chip on the adapter, but once I got one that worked it didn't seem to be fussy about brand of drive (although I
didn't test extensively).
I would guess the IDE to M.2 are really M.2 SATA not M.2 NVMe (ie just SATA
in a different form factor), so the above would apply to them also. M.2
SATA is getting rarer now as NVMe is so popular.
Generally speaking flash devices which have reached their wear limit go read only, but they can also just fail to be detected one day. I don't think
it's brand dependent, it's more to do with the failure mode, eg a power
glitch could zap them.
(I managed to bend a micro SD card by stepping on it the other day - I could see it trying to initialise, but I suspect I had snapped all the wiring to
the flash chip so the controller was there but couldn't find any storage and
so gave up)
I'd probably just buy (micro) SD cards and give them a try. I recommend
going for 'industrial' (better) or failing that 'high endurance' cards as
they are supposed to be more robust. eg Sandisk Industrial or Kingston Industrial:
https://www.cclonline.com/sdcit2-16gbsp-kingston-industrial-16gb-microsdhc-card-class-10-uhs-i-u3-v30-a1/
(be wary of buying from 'marketplace' sellers on eg Amazon/ebay/Aliexpress,
as they often have fakes)
Micro SD cards should work in an SD/MMC slot via an adapter, although if you get
problems it's worth changing the adapter.
Another option are the Raspberry Pi branded cards, which supposedly they
have put some better quality control into. Not tried them myself but:
https://thepihut.com/products/noobs-preinstalled-sd-card
(you will of course be reformatting the card so what data is supplied on it doesn't matter)
If you don't get anywhere with SD cards, the next thing to try would be an
IDE to SATA adapter plus a SATA SSD. They tend to be much more robust than
SD cards, but it adds the adapter as another variable.
I believe once upon a time CJE had some IDE to SATA adapters that worked
for Risc PCs. Not sure if they've tested on A9home but could be worth
asking if you don't fancy doing trial and error yourself.
Theo
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