Troubleshooting: Sector/byte mismatch on mac



I am running Mac OSX 10.4.9 (fully updated), using a firewire Lacie d2 DVD burner (newest tsstCORP model, with updated firmware) and have used several burning programs from, toast 6 -8 (mostly 7), Disco, Disk Utility. i am using both tayo yuden-r and verbatim media+r (both4.7gb) at 4x, 8x and 16x

All of my discs burn fine. But on verify (in toast) i get a "mismatch at byte 633/ sector xxxx. it is always byte 633, but a different sector everytime. this has happened on the last 20 discs i have burned. prior to that i had a 100% sucsess ratio.

i also use kdiff to compare originals to burns to see which ones are messed up. the strange thing is that using the same set of data, each time one or multiple files will be different, never all of the same files and always at byte 633 of a random sector no matter what app, what data or what media or what port (firewire 400, 800 or usb), what source drive, or what user account. sadly, i have only one machine to use the drive on.

i should note that the data plays but has errors.

So I, ran disk utility, fixed permissions, reset buses, ran disk warrior, ran cocktail, to no avail. after speaking with a tech at lacie (who was super nice), we determined the drive was defective. so i brought i back and got another one. i brought it home all new and shrink wrapped. i open it up, update the firmware, slap in a blank and… same thing. it wasn’t the drive…

i am in a bind because i can not reformat my drives and machine until i burn some data off.

what do i do? does anybody have any suggestions? any further courses of action i can take? help!


right now, i am able to compile dvds of unsuccessful burns. so if there are three files, on the first burn 1 & 2 will mismatch, but 3 is fine. on the second burn file 3 will mismatch but 1 & 2 will be fine. so with these two disc i will have at least one set of intact files. it seems random in what files the errors occur in. but still the same error noted above everytime.

this leads me to believe that there are not corrupted sectors on the hard disk causing the problem. which really has me stumped.

also, in the last hour, i have switched out the power supply with no luck.


Only thing I can think of is failing RAM…

If you burning program buffers the file to ram before writing then it is possible that it is buffered in the failing area and corrupting the data.

To be sure, run a memory test and also try the burner on another mac.


What kind of data are you burning? Are you using your computer while burning? OS X has a lot of invisible files that change often so that may be a reason.


Thanks for the responses guys.

qwakrz, after reading your response, the problem was definitely my ram. i upgraded my ram about a year ago from 512mb to 1.25gb. after removing the gb stick, and putting back the original 256mb i have burned 6 dvds flawlessly.

Since i upgraded have burned at least 200 dvd’s with out issue so it is pretty strange that this would happen out of the blue. Does ram just wear out?

really sucks too, as i have one of those 1.25ghz powerbooks that takes a specific bus slewing ram, which is scarce and expensive. The stick i bought was the exact same thing i would get from apple (minus $300 off price tag). so i am not really sure what to do.

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