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Why does it take forever to delete from CF?
I am running Windows XP - SP2 and have an 8GB CF card by A-Data 120X. I have a card reader in the PC, and when I check the device manager, I have "Standard Enhanced PCI to USB Controller" and some USB Root Hub devices. It's USB 2.0 I believe..

I copied 397 JPG's from the card to the hard drive and it only took about a minute or so..

I then wanted to delete the files off of the CF card, so I brought up Windows Explorer, right clicked on the CF Drive, then chose delete. It took 4 minutes, 29 seconds to delete 397 files. What gives?.

Why does it take forever?.

Next time I will just remove the card and format it in the camera. That only takes seconds..

Any suggestions?..

Comments (7)

The computer science answer: the algorithm is stupid, in it's attempt to be careful about editing directory entries. Writing sectors on flash is slower than reading, so you usually want to save up a series of writes in the same area so you only write it once. Kinda like editing 300 typos in a long document, then printing the whole fixed document (or just the affected pages) once. But Windows is trying to be careful (read, lazy and stupid): they delete each file completely, which involves rewriting several different areas with very minor changes; also, due to the way the file system works, they have to scan down the list alphabetically from the beginning on each deletion. Kinda like reprinting the five affected pages every time you fix each typo..

The short answer: Windows is stupid..

[ e d @ h a l l e yc c ] http://www.halley.cc/pix/..

Comment #1

GaryK1 wrote:.

Next time I will just remove the card and format it in the camera.That only takes seconds..

That's what you should be doing, anyway. Reformatting the card in camera is the best way to ensure ongoing reliability of the file system on the card..

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window..

Comment #2

Ed Halley wrote:.

The computer science answer: the algorithm is stupid, in it's attemptto be careful about editing directory entries. Writing sectors onflash is slower than reading, so you usually want to save up a seriesof writes in the same area so you only write it once. Kinda likeediting 300 typos in a long document, then printing the whole fixeddocument (or just the affected pages) once. But Windows is trying tobe careful (read, lazy and stupid): they delete each filecompletely, which involves rewriting several different areas withvery minor changes; also, due to the way the file system works, theyhave to scan down the list alphabetically from the beginning on eachdeletion. Kinda like reprinting the five affected pages every timeyou fix each typo..

The short answer: Windows is stupid..

I thought when a file was deleted, only the directory entry was written over. Are you saying that for CF cards, they overwrite the file, but on an internal hard disk, they just delete the entry?.

I guess reformatting is going to be the job of the camera!.

[ e d @ h a l l e yc c ] http://www.halley.cc/pix/..

Comment #3

GaryK1 wrote:.

Ed Halley wrote:.

The short answer: Windows is stupid..

I thought when a file was deleted, only the directory entry waswritten over. Are you saying that for CF cards, they overwrite thefile, but on an internal hard disk, they just delete the entry?.

No, I don't believe the actual file is written over, just the directory entry..

However, flash memory devices use wear balancing, whereby any particular block is not repeatedly written to, instead, a copy of the data is written to a new unused area of the card. The result is that writing large files is quite fast, but updating a small item is relatively slower. Possibly in order to update a single entry in the file directory (list of files on the card) a fresh copy of the entire table is copied and written to a new area of the card..

I may be wrong here, but if this is correct, to delete a single file, the entire list of 300 odd files is rewritten. So deleting 397 individual files could involve writing many thousands of directory entries..

The answer is to reformat instead of delete. It is possible to reformat using a card reader, but is not recommended. Use the camera to reformat instead..

I guess reformatting is going to be the job of the camera!.

Agreed..

Regards,Peter..

Comment #4

GaryK1 wrote:.

I am running Windows XP - SP2 and have an 8GB CF card by A-Data 120X.I have a card reader in the PC, and when I check the device manager,I have "Standard Enhanced PCI to USB Controller" and some USB RootHub devices. It's USB 2.0 I believe..

I copied 397 JPG's from the card to the hard drive and it only tookabout a minute or so..

I then wanted to delete the files off of the CF card, so I brought upWindows Explorer, right clicked on the CF Drive, then chose delete.It took 4 minutes, 29 seconds to delete 397 files. What gives?.

Why does it take forever?.

Next time I will just remove the card and format it in the camera.That only takes seconds..

Any suggestions?.

I figured out why the CF card took so long to delete files. The card was damaged. I took another CF card, a 4GB Transdata card which had over 300 files on it, placed it in the card reader and then deleted the files the same way I did with the 8GB card. Files were gone in seconds..

So the deleting does erase entries in the FAT table, just the memory card was damaged. I then tried 4 other cards, same thing, files gone in seconds..

Took the original card back to the store for a refund. All is well now ..

Comment #5

Glad you solved your problem. I just wanted to emphasize, as others have, the importance of reformatting your memory cards in the camera. Always do it in camera, never on the computer. And, unless you're desperate, never delete images from your card while it's in the camera.Too many subjects, not enough time.....

Comment #6

Surprised nobody mentioned this, but I always thought that when you delete something the file is just marked as "free space" and overwritten when new stuff is written to it...

Comment #7

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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