Home Forums Peripherals & Multimedia Peripherals Optical drives do not recognise some discs

I hope someone can advise me how to overcome a longer term problem I have been having with DVD-RAM discs not appearing on my desktop even though they have been burned by the drives that they are in.

I have a Mac G4 running OS 10.5.8. DVD-RAM disks are not recognised when mounted ie they do not appear on the desktop even tough the finder Preferences file has all boxes ticked. This can often be overcome by rebooting the system. Is there any program that can investigate/correct this? As the DVD does not appear on the desktop, there is apparently no means of accessing the DVD using proprietary programs such as TechTool Pro. Hope some one can help/advise what to do in such circumstances. I have three means of writing discs. Two are external (LG GSA-4120B (see below for details) and an LG GAS-E10N). I also have an internal disk drive (MATSHITA PD-2 LF-D110) which always seems to work though it won't accept the DVD-RAM discs I use (RAM4.7).

HL-DT-ST DVDRAM GSA-4120B:

Firmware Revision: A117
Interconnect: FireWire
Burn Support: Yes (Vendor Supported Drive)
Profile Path: VendorSupport.drprofile
Cache: 2048 KB
Reads DVD: Yes
CD-Write: -R, -RW
DVD-Write: -R, -RAM, -RW, +R, +R DL, +RW
Write Strategies: CD-TAO, CD-SAO, CD-Raw, DVD-DAO
Media:
Type: DVD-RAM
ID: Matsushita Electric Industrial CO.,LTD. M01J3003
Blank: Yes
Erasable: No
Overwritable: Yes
Appendable: Yes
Write Speeds: 3x

Please advise possible solutions if you can.
regards

You may have a corrupted preference file. Move ~/Library/Preferences/com.apple.finder.plist to the desktop and then log out/in (or restart). Reset your Finder preferences. If the problem is solved, trash the bad plist. If not, move it back and log out/in again.

Many thanks for your reply to my problem with the disc not being recognised. I tried what you suggested and found that the situation was unchanged. The disk utility indicates for that drive that it is waiting for a disk to be inserted and will open the drive when I click open. Is there anything else I could try?

I can think of several possibilities that may be responsible for your problem:

1. Are the disks that are not showing up DVD-RAMs you have "burned" yourself? If so then consider this:
   1. Commercial DVD-RAMs are mechanically stamped, not burned. The stamping process creates microscopic pits in the disc surface that cause a change in the reflected light from the "read laser"
   2. Burned discs approximate that change through the use of dies that change colors when exposed to the "write" laser
   3. Estimates are that fewer than 30% of burned discs are readable on all readers.
   4. The readability is a function of:
      1. The dies used in the media
      2. the reflective substrate of the disc
      3. the frequency and strength of the "write" laser
      4. the frequency and strength of the "read" laser
   5. If these are all "burned" DVDs you might try using a higher quality (generally that means more expensive) blank and see if your results improve.
2. If the failure to read is only occurring on one reader then:
   1. The read lasers may be dirty and cleaning them with a commercial DVD player head cleaner may help
   2. The read lasers are weak or failing and the drive will have to be replaced.
3. If neither of the above are true then:
   1. Start up in Safe mode by:
      1. Be sure the computer is shut down.
      2. Press the power button.
      3. Immediately after you hear the startup tone, press and hold the Shift key. Tip: The Shift key should be held as soon as possible after the startup tone but not before.
      4. Release the Shift key when you see the gray Apple and progress indicator (looks like a spinning gear).
   2. If the discs read after a Safe boot then the problem is most likely the result of a third party extension. Identifying the culprit in that case is mostly a matter of trial and error but post back here and someone can help you narrow down the list.
4. Try using something like Cocktail, OnyX, or TinkerTool System to flush out all the various system cache files. (Be sure you use a version of you chosen utility that is compatible with OS X 10.5.8 and the G4 processor.
5. Try disconnecting all external devices except the keyboard and mouse.

Many thanks for your comprehensive reply to my problem.Gives me quite a lot to consider particularly aspects that I didn't know about DVD-RAM disks. I am using Memorex disks but don't know if these are the best.
It isn't one reader that is affected and it isn't always the same situation ie most disks seem to be recognised on start-up though often not once the system is running ie I often can't swap disks ie eject and insert and for the disk to be recognised. I will try cleaning as you suggest (any recommendations re-which player head cleaner to use?). I will also try the safe start-up.
Thanks again for your help. Will let you know any improvements!

Unfortunately, based on many posts in these forums and their predecessor MacFixIt forums, Memorex blanks have been questionable at best. What usually happens is that they burn OK (that is, there may be no errors in the burning process), but sooner rather than later reading them becomes problematic. This can happen as early as some months after burning.

The confusing part of this is that there is little to predict what's going to happen: at a certain point in time a particular disc may (seem to) be OK in one drive, and unreadable in another. A month (or a year) later the disc may be unreadable anywhere. Another disc from the same batch may behave quite differently, even though it has been treated 'the same way'. Superficially, there seems to be no rhyme or reason to what's going on.

The stability of a particular brand of blanks depends on the production process, associated quality controls, and the way the the blanks are being stored. The latter becomes really important after burning, and variations in storage regimen (temperature, light, moisture, dust etc.) markedly affect a disc's longevity.

There are known reliable as well as unreliable brands. The former tend to last longer, even though here too you may run into occasional burning issues (i.e., not associated with burner problems). The unreliables invariably konk out within a few years after burning, although there may be the odd exception. Over time, some brands' quality may deteriorate, others improve. This is because of variations in production location and quality; many brands don't produce themselves, but buy from 3rd parties and may change sources repeatedly.

FWIW, I've been using Verbatim for over 10 years, and I have yet to encounter a disc that wouldn't read once they came out of the burning process OK. I also have/had a number of Memorex discs, most of which stopped being readable within years after burning. I copied them to Verbatim as soon as I ran into the first unreadable disc. Since then more of these Memorex discs stopped being readable, but I still have a few that seem to be OK. The Verbatims are still going strong, but here too I don't expect the eternal life.

Others here may chime in with their experience regarding 'good' or 'bad' blanks, but generally you get what you pay for.

Just to show what variation there is among blank media, I have had good results with Verbatim discs as alternate has, but since I use a LIghtscribe burner to label my discs Verbatim or HP discs are the only options available and so far the Verbatims have been completely reliable (I have my fingers crossed).

Disc failure over time is often the result of deterioration of the reflective media. The protective outer plastic covering of the disc is often thin and/or relatively porous allowing oxygen to bleed through and oxidize the what is generally an otherwise unprotected aluminum foil reflective media. So called archival quality optical media (CDs and DVDs) use gold anodized foil or even actual 24K gold foil because of gold's resistance the oxidation. I would speculate the difference in my experience and alternaut's with Verbatim discs may be due to differences in the media necessary to support burning the label on the reverse of the disc.

CD/DVD media is, IMO, one of those cases where you get what you pay for.

Hi, thanks for your reply re-disk types. I will get Verbatim next time! Meanwhile I will endeavor to clean my drives!

This only applies to CDs, and the close proximity of label and metal/dye layers here is the reason why labeling CDs can negatively affect the data integrity of the disc. In contrast, both sides of DVDs are covered with polycarbonate, as if two thin CDs were glued together at the reflective metal layer. See this optical disc structure overview for details.

Hi, I'm back having got a cleaner and Verbatim discs which are new but I find are not recognised by the Mac particularly in the one with the USB connection. The other drive is better and I have succeeded in establishing one of the new discs but still have the problem that I can only get them recognised when starting up from a shutdown Mac. Any other ideas?

This is something of a laundry list of troubleshooting steps you can try to at least narrow down the problem if not solve it.

1. Try to mount one of the discs open /Applications/Utilities/Console and check the console log to see if there is any entry regarding disc mounting. If you find something copy what you find and post it back here.
2. Sometimes otherwise inexplicable problems can be solved by a good general housecleaning. Using a version that is compatible with OS X 10.5.8 run Pilot in Cocktail, Automation in OnyX, or Caches in TinkerTool System to repair permissions, and flush all the system and user cache files then reboot your system.
3. On the chance the problem is caused by conflicting software or drivers, Safe Boot your system by
   1. Be sure the computer is shut down.
   2. Press the power button.
   3. Immediately after you hear the startup tone, press and hold the Shift key. Tip: The Shift key should be held as soon as possible after the startup tone but not before.
   4. Release the Shift key when you see the gray Apple and progress indicator (looks like a spinning gear).
      
      Safe boot loads only required kernel extensions (some of the items in System/Library/Extensions) and disables all startup items and any Login Items. So if this solves the mounting problem at least you will know where to start looking for the culprit. After that it becomes largely a matter of trial and error to identify the specific problem cause.

Thankd for your reply. I did No.1 and got
Dec 6 14:35:08 robert-scott-kerrs-power-mac-g4-agp-graphics ReportCrash[2828]: Formulating crash report for process CleanApp Daemon[2829]
Dec 6 14:35:10 robert-scott-kerrs-power-mac-g4-agp-graphics com.apple.launchd[1] (com.synium.cleanappdaemon[2829]): Exited abnormally: Bus error
Dec 6 14:35:11 robert-scott-kerrs-power-mac-g4-agp-graphics ReportCrash[2828]: Saved crashreport to /Library/Logs/CrashReporter/CleanApp Daemon_2011-12-06-143458_robert-scott-kerrs-power-mac-g4-agp-graphics.crash using uid: 0 gid: 0, euid: 0 egid: 0
Dec 6 14:35:28 robert-scott-kerrs-power-mac-g4-agp-graphics kernel[0]: { 41 910440} UniNEnet::restartReceiver

having first cleared the display. Any help?

Hi, I tried starting up in safe mode that didn't seem to make any difference. The disc programs such as Cocktail don't appear to show or recognise discs on the DVD drives so I didn't get far with that. The question of whether the RAM discs are recognised seems to be a bit spurious and apart from starting up from off there isn't any rule whether the disc is recognised or not. Are there any programs that simulate the condition of start up?

Nothing apparent here other than the CleanApp Daemon is crashing on launch. Which shouldn't have any impact on disc recognition. The CleanApp Daemon monitors and records software installations to make it faster, easier, and more certain what files to delete when you trash an application. Be sure you have the latest version of CleanApp which is 3.4.8 and the first time you launch it be sure to allow it time to rebuild its database if necessary.


That would tend to eliminate any third party drivers, etc that might interfere with reading a disc.


My suggestion of using Cocktail was to flush out all the user and system cache files. There are cache files that may have an impact on reading disc data.


Not that I know of. However, you can boot up in the verbose mode which will display much of what is going on during the boot process on your screen by

1. Shut your computer completely down (do not reboot)
2. Press the power button to start
3. Immediately press and hold Command+V

I don't know why this has not been suggested before, but physically disconnect (unplug the USB, or firewire cables) from your computer and see if the internal drive reads reliably. Then add the external drives back — one at a time — testing the internal drive and the external drive(s) and see what happens. Connect the drives directly to the computer and not through any hubs, even those in the Apple keyboard and do not daisy-chain through other drives.

> I don't know why this has not been suggested before, [....]

I don't know about you and others, but I've found myself forgetting about some pretty basic troubleshooting steps lately, which I've attributed to the long dearth of posters with basic issues.

Personally, I had a ball when grelber first got his iMac and was asking questions the likes of which we haven't heard in ages.

Thanks for your continued interest in my disc problem. I will try starting in verbose mode and see what that shows.
I am not sure that I can disconnect the external discs from hubs and connect then directly. The internal disc has never given any trouble; it is a pity that it will not accept Type 2 discs. I use LaCie double sided/Type 1 5.2 GB discs there.

Surely you can at least connect the external drives directly to the computer one at a time. Your problem could easily be caused by a faulty hub, faulty USB or Firewire connector cable, too many connections in the daisy chain, or even one of your drives not playing nice with the others.

Hi, I have tried the start-up in verbose mode but it goes past so quickly that I could do with a download of what comes up to be able to study it. Is this possible? What should I look out for?

I could disconnect the drives individually if there is one that can be relied upon not to work. In fact they do seem to work on most occasions with pre-recorded discs, eg the lens cleaning disc, audio etc.