How to reformat a compact flash?

[awatt]

After using an image recovery service, it was recommended I reformat the flash. How do I do this?

 

[manning]

Put the card back into the camera and reformat it. The camera manual should have the instructions. Very simple to do. It is advisable to format only in the camera.

 

[Frantasmic]

May I ask why it is advisable to only format in the camera? I usually use the mini-drive on the computer. What is the difference?

 

[boBQuincy]

Formatting a memory card in the reader can cause problems. The default setting on my PC is FAT32, which my Canon 10D is not supposed to read.

I usually do format my cards in the reader to get the best results, but I am careful to use FAT. One day I might forget and use FAT32 and the card may not work in my camera, unti reforatted with FAT.

The PC does a full format which completely wipes the card as opposed to the quick format which only removes some of the file header information. A quick format would probably not clear out any corrupted space on the card but a full format would.

Afaik, most cameras only do the quick format.

Choose your format style, but be careful!

 

[0bli0]

the camera will generally specify the appropriate cluster size. also, some older cameras are very finicky about formatting. formatting in camera is quick and ensures that new data isn't written to the same set of NAND cells every time. using the computer to 'delete' images doesn't. with today's flash memory, it really doesn't matter but older CF (like in the days of 32 meg cards) it was very common to 'wear out' cards as they were often only rated for 5,000 cycles. today's memory card cells are rated in excess of 100,000 cycles and the onboard controllers automatically map bad cells. sure you may find that after 100,000 pictures, your card may have decreased capacity, but not by very much - because formatting ensures random cell usage.

btw i always format in-camera. it's just 3 clicks through the menu.

 

[Amy]

Is formatting necessary? Should I format a band new SD card or just use it straight out of the package?

 

[0bli0]

you can use it straight out of the package

 

[MarkBarbieri]

I rarely format my cards. I usually just cut and paste the photos onto my computer and stick the card back in the camera. I haven't had any problems yet. I typically only do a format when I'm moving the card between cameras or camcorders.

 

[Groucho]

The PC does a full format which completely wipes the card as opposed to the quick format which only removes some of the file header information.

For the record, a full format does NOT wipe a drive (including a memory card.) Data can still easily be recovered from a formatted card, hard drive, etc.

If you wanted to completely wipe a card, you'd need a tool that is designed for wiping data. Hard drive manufacturers have such things downloaded and there are others - I sometimes use Active@ Kill Disk as there's a free version that works on most any hard drive out there (but wouldn't work on a memory card as there are no USB drivers, I don't think, and these tools generally run from a bootable floppy or CD.)

I'm pretty sure that the wiping programs that run from inside Windows would work fine with memory cards. There are probably ones advertised specifically for camera memory cards, but any that work inside Windows would work fine, since there's nothing special about a memory card that makes it different than any other removable drive.

 

[Groucho]

I rarely format my cards. I usually just cut and paste the photos onto my computer and stick the card back in the camera. I haven't had any problems yet. I typically only do a format when I'm moving the card between cameras or camcorders.

This is usually fine as long as you give it a minute or so after removing the pictures from the card. The danger of just yanking it out is that, if the computer is still writing to the card (like when deleting a picture), and you yank it in the middle of the operation, you could have some corrupted data on there. It may seem to work fine but one or two new pictures may be unreadable, etc. If you used Windows 95/99/ME, you may have seen scandisk running after your PC crashed and you rebooted it - that it designed to fix those kind of problems (and yes, you can scandisk your memory card, but the WinXP equivalent is chkdsk.)

If you are using a memory card reader that's inside your PC, you should right-click the drive letter that it uses and hit "eject" before removing it, that will tell the computer to finish writing and not try to access it again. If you are using an external reader (including the camera itself), go to the system tray (by the clock, usually in the lower-right corner) and look for the "safely remove hardware" icon, click it, and tell it to safely remove the card. It will tell you when it's safe to disconnect it.

 

[0bli0]

the other potential problem with deleting from the pc is that is you're using the same exact flash cells every time (which are formatted into sectors and clusters). generally speaking it's going to be fine and you'll still purchase a new media before it dies.

you may want to format once in a while to have the card randomly distribute the clusters across the cells. especially if you occasionally see corrupted images.

 

[Groucho]

the other potential problem with deleting from the pc is that is you're using the same exact flash cells every time (which are formatted into sectors and clusters). generally speaking it's going to be fine and you'll still purchase a new media before it dies.

you may want to format once in a while to have the card randomly distribute the clusters across the cells. especially if you occasionally see corrupted images.

Are you sure about that? A memory card ought to be like any other storage device. Formatting puts the same partition information in the same place and the camera and PC will always try to write data sequentially on a brand-new, empty partition in order to minimize fragmentation.

 

[0bli0]

yes - very sure - i didn't believe it either as it goes against 20 years of experience working with FAT tables and drives.

i actually found out as the parent company i work for is part of the CompactFlash association and also from SanDisk when they replaced an old 64 meg 'pre-controller' card.

although the interface is still ATA standard, the on-board controller responds to a quick format by doing the following:
1) testing all memory cells on the device
2) marking cells bad in the controller's map
3) set aside spare cells to replace bad cells that may fail
4) create the FAT, ensuring randomisation across cell quads
5) reserve cells for use by the storage device's controller (like camera firmware notification, etc.)
6) reserve cells for specific functionality ( security keys in SD cards is one example).

every manufacturer's controller chip uses slightly different algorithm for randomising.

 

[Groucho]

Bizarre. Is that true for all flash-based media (like SD, Memory Stick, regular USB drives, etc) or just CF?

I agree that it goes against everything that we've learned in the past!

 

[0bli0]

i know it pertains for CF & SD and most USB flash drives. i think the controllers were first introduced around '98 or '99.