handyfloss

Remember how MacOS X ate my pics? In that post I explained that Linux had problems with >1 GB Secure Digital cards.

Well, apparently the problem was in the card reader, not in Linux (or the card itself). I recently acquired a SD card reader on eBay (actually, one like this one), and with it I can mount and read 2 and 4 GB SD cards without problem.

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Perhaps you are aware of my first (and last so far) gripe with DreamHost: as I wrote a couple of months ago, they wouldn’t let me use my account space for non-web content.

Well, it seems that they really work to make their users happy, and probably other people requested something like that, and read what the August DH newsletter says about it:

In keeping with my no-theme theme, uh oh, I think I just made a destroy-the-universe-LHC-style self-contradiction, here’s a new feature that pretty much has nothing to do with anything I said in the introduction!

https://panel.dreamhost.com/?tree=users.backup

Now, you know how we give out a LOT of disk space with our hosting? Well technically that space is only supposed to be used for your _actual_ web site (and email / database stuff) .. not as an online backup for your music, pictures, videos, other servers, etc!

Well, just like every other web host does, we’ve been sort of cracking down on that some lately, and it seems to catch some people by surprise! Nobody likes being surprised, especially in the shower, which is where we typically brought it up, and so now we offer a solution:

You CAN use 50GB of your disk space for backups now! The only caveat is, it’s a separate ftp (or sftp) user on a separate server and it can’t serve any web pages. There are also NO BACKUPS kept of THESE backups (they should already BE your backups, not your only copy), and if you go over 50GB, extra space is only 10 cents a GB a month (a.k.a. cheap)!

Thanks, DreamHost, for showing me that I made a good choice when I chose you!
Update: apparently only SFTP works (or FTP if you are idiot enough to enable it), but not scp or any SSH-related thing (rsync, …). I hope I find some workaround, because if not that would be a showstopper for me.

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OK, so the 2GB SD card I use in my camera has its problems. Apparently, only 1GB of it are recognized by the OS (Linux) and/or the card readers I own. The problem seems to be common, as you can see by googling about it. More info, from the Wikipedia article for SD cards:

Devices that use SD cards identify the card by requesting a 128-bit identification string from the card. For standard-capacity SD cards, 12 of the bits are used to identify the number of memory clusters (ranging from 1 to 4096) and 3 of the bits are used to identify the number of blocks per cluster (which decode to 4, 8, 16, 32, 64, 128, 256 or 512 blocks per cluster).

In older 1.x implementations the standard capacity block was exactly 512 bytes. This gives 4096 x 512 x 512 = 1 gigabyte of storage memory. A later revision of the 1.x standard allowed a 4-bit field to indicate 1024 or 2048 bytes per block instead, yielding more than 1 gigabyte of memory storage. Devices designed before this change may incorrectly identify such cards. Usually by misidentify a card with lower capacity than is the case by assuming 512 bytes per block rather than 1024 or 2048.

For the new SDHC high capacity card (2.0) implementation, 22 bits of the identification string are used to indicate the memory size in increments of 512 KBytes. Currently 16 of the 22 bits are allowed to be used, giving a maximum size of 32 GB. All SDHC 4-GB and larger cards must be 2.0 implementations. Two bits that were previously reserved and fixed at 0 are now used for identifying the type of card, 0=standard, 1=HC, 2=reserved, 3=reserved. Non-HC devices are not programmed to read this code and therefore cannot correctly read the identification of the card.

All SDHC readers work with standard SD cards.[ref]

Many older devices will not accept the 2 or 4 GB size even though it is in the revised standard. The following statement is from the SD association specification:

“To make 2 GByte card, the Maximum Block Length (READ_BL_LEN=WRITE_BL_LEN) shall be set to 1024 bytes. However, the Block Length, set by CMD16, shall be up to 512 bytes to keep consistency with 512 bytes Maximum Block Length cards (Less than and equal 2 Gbyte cards[ref].”

I have had problems in the past with this issue, and could only retrieve the photos exceeding the “first GB” of the card with a tedious operation: copy some photos from the card to the internal memory of the camera (28MB), remove the card from camera, connect camera to computer, download the photos in the internal memory (and empty it), unplug and repeat. 1GB/28MB = boring as hell.

However yesterday I realized that I had a shinny MacBook with its MacOSX intact. I read somewhere that Windows would sometimes read 2GB cards that Linux couldn’t, by the simple method of happily ignoring the f*cked up file system in them. Maybe MacOSX could, too.

Well, it turns out it couldn’t. When I attached the card in the card reader (I didn’t try with the camera directly), MacOSX found the device and mounted it, giving me a nice icon in the Mac version of “My PC”. However, the directory the icon led to was empty. I thought “Tough luck, Mac reads nothing in the card”, unmounted it and unplug it. Then I placed it in the camera again, turned it on and… there was no photo in the darned thing! MacOSX had erased them!

There is still the (likely) possibility that I made some deep mistake, but the explanation for now seems that MacOSX ate my pics. Sad.

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