Vista "Live filesystem" DVD (UDF format) writing problems ("read only" disc that was/should be writable)?

[QuixoticOne]

So yesterday I was making some backups and thought I'd give the "live filesystem" UDF non-mastered mode of "drag and drop" writing of arbitrary files to a DVD a try.

I loaded a fresh single layer DVD+RW disc, formatted it, and started dragging miscellaneous files / folders to it.

It all went pretty well and the files apparently wrote to disc as expected for the first several thousands of files / dozens of folders, et. al.

Then when I had only around 1GBy to 900MBy range of free space left on the disc (as determined by right clicking the disk in the "Computer" list and looking at its Properties), I tried to add a last set of a files to fill up more of the free space on the disc; I made sure there would actually be enough room for them first.

After a few moments of starting to copy them I got an error dialog telling me that I could write the files to DVD, but that the current disc is read only and that I'd need to insert a writible disc to proceed.

I didn't do anything to make the disc "read only" and now it refuses to let me write any more data to that DVD+RW disc though I had been successfully writing to it many times.

I tried closing the session but that did not help it become writable again. Now it does appear that it successfully (at a glance) wrote most of the data to the disc, but I am not impressed that I've encountered this "read only" bug.

Has this happened to anyone else?

I'm running Vista 64, SP1 RC, 6001.18000....1840, and have applied all relevant available patches / updates, so apparently this is a standing problem with Vista that isn't corrected by any fix AFAIK.

Since "file copying" performance was one main issue supposedly improved in SP1, I'll say this additionally -- for copying LARGE files (several megabytes) it often seemed to perform fairly well and get transfer rates to disk in the 1MB to 4MB/sec range, decent enough, I guess for an 4x DVD+RW burn. However sometimes for a long stretch at a time it would seem to barely be writing (the DVD drive activity LED was intermittently active, but mostly not), and in "Resource Monitor" the "disk" I/O transfer rate was down in the 287kBY/sec range, pretty unacceptable. As I recall this was mostly when it was copying many (thousands) of small (few kilobyte) files.

The relatively bad burning performance was sometimes annoying, but maybe forgivable (it's too early to say for sure) if it had actually WORKED reliably until the disc was effectively full.

 

[nerp]

Have you been able to replicate the issue repeatedly? What kind of media are you using? You sure you didn't accidentially hit some kind of keyboard shortcut or cause an errant yet unnoticable click to close the session? Just a thought... I've accidentially dragged/moved files around without realizing it just from the slip of a finger.

 

[QuixoticOne]

Originally posted by: nerp
Have you been able to replicate the issue repeatedly? What kind of media are you using? You sure you didn't accidentially hit some kind of keyboard shortcut or cause an errant yet unnoticable click to close the session? Just a thought... I've accidentially dragged/moved files around without realizing it just from the slip of a finger.

No, I haven't tried to replicate the issue yet, though I'll look into it later.

I'm using Memorex DVD+RW 2.4X discs, I don't know the actual media vendor / product code IDs offhand.

I'm pretty sure I didn't manually inadvertently close the session, and even if I had, I'd ASSUME I should / would still be offered the chance to transparently or after accepting a prompt continue writing to the medium in a second session which would include the contents of the previous one.

The PC went to sleep IIRC a few times during idle periods in my various backup episodes (with the session still open); I thought maybe that'd be the end of the story since I didn't have faith in their ability to continue after that, but IIRC it did keep working after I woke it up and resumed writing things.
The USB DVD drive itself has remained ON, though.

Yes it's unfortunate how easy they made it to accidentally drag / move files around in their explorer interface, that happens to me too sometimes. I wish they'd fix it. Even just having a little button you can press that says "READ ONLY" or something when you're BROWSING without intending to DELETE/RENAME/MOVE anything.

I wonder what it'll take to get the disk working again.. surely I shouldn't have to reformat it to keep writing. I almost wonder if I hit some 4GB limit bug though that seems unlkely..... I'll go play with it more...

 

[QuixoticOne]

Update: Well nothing else worked, so I told it to "safele remove" the USB DVD writer.
It wouldn't, and said some program was still using the disc. Nothing I had open was accessing the drive, though, so it must be something inside Vista that was incorrect or locked up.

Then I told it to "eject" which it did, and then I reloaded the media. It then loaded it and asked me if I'd like to repair the disc because it detected some corruption possibly due to its not having been unmounted properly. So I let it run its chkdsk on the disc, and it did find/fix (so it says) some errors.

Now it is letting me write to the disc again.

So the essence of the story is apparently that DVD live filesystem writing in Vista isn't a very safe or reliable process, even with SP1 installed.

Also I've noticed more about the slowness. This disc has 30,425 files in 5049 folders.
Apparently over 2000 of those folders are empty of files because I sat and watched
it accumulate the "files" and "folders" counts after I selected all the disc files in explorer and right-clicked to the "Properties" menu item. For a LONG TIME the file count didn't change while the folder count increased SLOWLY.

Actually it appeared to be reading in new (EMPTY!) folders at a quite consistent rate of about 10 per second of real time; the DVD drive's access light was barely even on; it was reading these empty directories INCREDIBLY slowly.

I used a timer to check how long it'd take from start to finish for it to calculate the "Properties" of every file on the disc; it took 8 minutes and 12 seconds to count the number of 30425 files and 5049 directories (half being empty, and that being the SLOW part), and accumulate the total numbers of files / directories / bytes of data represented by the files. The vast majority of that time seemed to be spent in counting empty files at a rate of 10/second.

This was on an idle Q6600 system with 8GB RAM and on a USB 2.0 connection.
Pretty bad.

 

[Auric]

Writing on-the-fly formats in order of reliability, which is reduced by USB versus ATA due to extra overhead/translation:

DVD-RAM
DVD+MRW
CD-MRW
DVD-RW DRT-DM
DVD+RW
DVD-RW
CD-RW
CD-R

Ergo, I strongly recommend DVD-RAM for such purposes.