Everything Else

In order to assist "my backup" in protecting data in such storage devices, I'd like a compact flash card featuring a " write-protection "-lock-switch for data storage safety, something with the lock switch on the bottom side of the memory card prevents data from being tampered with when bad things happen, things like logical damages/data corruption due to file system crashes.

In case, I need a card with no less than 64Gbyte of storage capacity: tips? suggested-products?

thanks

i wouldn't use flash based devices for important backups at all. in my experience as far as reliability goes they haven't been great at all

I need something like "write once" "read many", I mean I'd like to clone the whole partition0 (windowsXp) inside the complact flash, switch it into write-protection, and keep it within the laptop in case of corruption damages in the windows partition

this way, instead of formatting and reinstalling all the applications (which is boring and wastes too much time)
I can switch into linux, and clone back the whole partition from the CF

thus, the compact flash won't be used for writing, it will be used for reading, at 50-80Mbyte/sec

PCMCIA static memory cards had a write-protect signal, but it only was a flag to the host controller to block writes to certain segments based on the Card Information Structure; it was not a hardware enable. The larger flash cards are seen as I/O devices (ATA disks), not memory; so the place to look would be the ATA specification. It appears that there is a PROTECT command in ATA. Some mSATA disks also have the function on a pin.

I was imagining the write-protection feature performed by the embedded disk controller inside the Compact Flash cartridge, I mean the feature can be triggered by an external lock-switch during the bootstrap of disk controller. Firmware matter in short

the question is: do these devices exist ?

I have opened this request

and found these two products

• CF300XSLC
• Cactus

step2, where to buy ?



the SD technology seems to have the write-protection switch

• SanDisk-Extreme-SDSDXPA
  Lexar-Professional-UHS

I do not know if the switch is read by the software (Windows XP driver?), or by the firmware (the built-in SD controller inside the SD card) …



p.s.
the CF pinout is reporting the /wr signal, what do you think about …
- checking if the CF can work in true-ide mode
- opening the laptop
- finding the /wr signal in the CF connector
- cutting it
- wiring it out onto a jumper, to be put inside the laptop as "write enabled/disabled"

does it sound too evil ?

full-size SD cards have a write protect notch that moves an optional switch in the socket. This is purely advisory: if the host driver ignores the switch GPIO input, writes can still occur. there is a set of commands that can be sent from the host to make the card read-only.

Cutting the ATA write strobe line will not work, since this is used for sending parameters and commands to the drive. ATA disks seldom have any means to prevent writes, which is the reason that expensive adaptors exist for the forensics industry that block writes to the disk. Sometimes a flash module has this same ability: this one calls it "virtual writes". The card performs write commands to its buffers but never saves the buffers to the media.
http://www.mouser.com/catalog/specsheets/apsdm.pdf

The CF specification defines pins for "Write Enable" and "Write Protect", but they do not do what you think. WP is a card output used for bus state signaling. /WE is ignored in True IDE mode. See here:
http://rumkin.com/reference/aquapad/media/cfspc3_0.pdf

What might work is putting a switch in the WP line of a CF-to-PC Card adaptor, used in PC Card Memory mode. If the host controller respects that signal, it will refuse writes to regions the CIS says are write maskable.