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Panasonic Working On 2-Terabyte SD Cards
An anonymous reader writes "SD cards with a theoretical maximum capacity of 2TB are in development by Panasonic and the SD Association, it has been announced. The technology is called 'Secure Digital Extended Capacity', or 'SDXC', and Panasonic has announced it will soon show off a 64GB SDXC card. Using the new technology, read/write speeds are set to hit 300MBps. SanDisk and Sony are using the same standard to develop Extended Capacity cards in Sony's Memory Stick Pro and Memory Stick Micro range. SDXC utilises Microsoft's new exFAT file system — AKA 'FAT 64' — which first appeared in Windows Vista SP1, and has a theoretical file size limit of 16 exbibytes."
Reader xlotlu adds a note about the "proprietary exFAT file system, which is available for licensing under NDA. There are currently no specific patents on exFAT, but its legal status is uncertain since it's based on FAT. The FAT patents have been previously upheld in court."
This article is absolute blithering bullshit. They're talking about the interface / file systems' _addressable_ size. Compared to actually achieving higher storage densities, that's about as hard as pulling a number out of the air. It has absolutely nothing to do with the technology needed to fit 2TB or any other number of bytes into whatever little card.
And oooh theyre making a 64GB card but "working on" a 2TB card? Yeah right, so only a 30-fold increase in density left to go!
Then he goes on to discuss throughput as if that has anything to do with it....
Don't let the name fool you. This is less a "FAT" file system than FAT32 was to FAT16. It barely resembled anything FAT AT ALL. Long file names are different. Storage is different. The boot sector layout is different. File entries are different.
A snippet from wikipedia (since I can't find a link to the specification right now):
exFAT is an incompatible replacement for FAT file systems that was introduced with Windows Embedded CE 6.0. It is intended to be used on flash drives, where FAT is used today. Windows XP file system drivers will be offered by Microsoft shortly after the release of Windows CE 6.0, while Windows Vista Service Pack 1 added exFAT support to Windows Vista. exFAT introduces a free space bitmap allowing faster space allocation and faster deletes, support for files up to 2^64 bytes, larger cluster sizes (up to 32 MB in the first implementation), an extensible directory structure and name hashes for filenames for faster comparisons. It does not have short 8.3 filenames anymore. It does not appear to have security access control lists or file system journaling like NTFS, though device manufacturers can choose to implement simplified support for transactions (backup file allocation table used for the write operations, primary FAT for storing last known good allocation table).
"When life gives you lemons, don't make lemonade. Make life take the lemons back!" -- Cave Johnson
Since Linux, Mac and even most existing Windows users won't be able to use exFAT/FAT64 formatted media, they're not doing anyone any favors.
They could use NTFS as a more common file system, except for that whole journaling burning up the flash thing.
The most reasonable alternative is ext2, though I wouldn't want to spend a day fscking a 2TB SD card any more than I'd want to spend a day with chkdsk on an exFAT formatted one.
If flash sizes are going to continue to grow, they need to deal with journaling filesystems. Perhaps the easiest, most cost effective way to do this is by pre-partitioning the unit, with the bulk of the storage in one partition, but a second partition for a much smaller external journal aligned to more robust flash (e.g., 128MB with a 50M+ write life). Even with a 5 second journal update interval, that would give you about 8 years of 24 x 7 x 365 usage. Ext3 supports this configuration, not sure about NTFS or HFS+.
Can You Say Linux? I Knew That You Could.
The problem with ext3 is the same as with NTFS. They are journaling file systems, meaning that they do a lot of read/writing to the media. This is no problem with hard drives but flash media have just a limited amount of these. That's why non journaling file systems are employed on them. Mainly some kind of VFAT but ext2 would also do the job quite nicely. Problem is, that ext2 is not supported on the Windows platform as a default option. Additional installation is not an option for the avarage Joe. The bigger media will have some sort for FAT for the same reason. I'm qurious, is this new version of FAT also readable on non Windows platforms? Anyway, if you feel like it, it should be no problem to reformat them to ext2. Just your Windows friends will look a bit surprised that it seems unformatted. If you go more into the thing, you probably can also partition that thing like normal USB flash media, put a standard VFAT in one partition to it's limit and fill the rest with ext 2 to 'hide' your info from your clueless friends / boss / whatever. Or you put an array of normal FAT partitions on it with their maximum limitations. Did I miss something?
Says Wikipedia "the SD 2.0 standard in SDHC uses a different memory addressing method (sector addressing vs byte addressing), thus theoretically reaching a maximum capacity of up to 2 TB (2048 GB). However the SD Card association has artificially defined the maximum limit of SDHC capacity to 32 GB"
Sounds like another way to extort people into using MS only standards. Hooray!
SD is more than MMC+DRM. It added the 4-bit protocol which is pretty different from the SPI-style that MMC used and which helped improve transfer speeds. There are also quite a number of changes to the protocol. The DRM seems to be pretty worthless anyway - does anyone actually use it?
On a sidenote, SDHC already has a maximum addressable space of 2TB (2**32 512-byte sectors), though it's limited to 32GB purely artificially by the wording of the spec. Methinks this is mostly marketing and not a real change.