About Buffer Underruns
CD writing is a real-time process which must run constantly at the selected recording speed, without interruptions. The CD recorder's buffer is constantly filled with a reserve of data waiting to be written, so that small slowdowns or interruptions in the flow of data from the computer do not interrupt writing A buffer underrun error means that for some reason the flow of data from hard disk to CD recorder was interrupted long enough for the CD recorder's buffer to be emptied, and writing was halted. If this occurs during an actual write operation rather than a test, your recordable disc may be ruined.
Possible Causes of Buffer Underruns
Hard Disk
- "Dumb" thermal recalibration.
- Fragmented hard drive.
- Sector size at 32kb instead of 16kb.
- Not enough space in temporary directory.
Hardware
- Slow source devices.
- Source devices that transfer data in bursts.
- Incorrect recorder controller settings.
- Inability of the devices to sync properly.
- Overall system configuration.
- Computer unable to allow fast enough data transfer.
- Old device drivers.
Memory Resident Programs
- Any program that may activate on its own
- Anti-virus software
- Screen savers
- System agents
- Schedulers
- TSR (terminate and stay resident) software
- Networks
- System sounds
- Animated icons
Networks
- Recording across the network (usually too slow to maintain adequate throughput speed).
- Incoming e-mail or faxes.
- Other people accessing your computer.
Windows 95
- Modify Virtual Memory Settings (see below).
- If you have more than 16 MB of RAM, disable Auto Insert Notification (see below).
- If you have more than 16 MB of RAM, change the hard drive's Typical Role to Network Server (see below).
Files to Be Recorded
- Recording many small files.
- Damaged source files (data loss).
- Trying to record files in use by the system or other applications.
Other
- Copying from a CD that is scratched, dirty, or damaged.
- Recorder malfunction.
Checks / Prevention
- Disable or remove everything in the computer EXCEPT the operating system, the recording software, and the drivers for your source devices.
- Defragment your hard drives at least once a week to prevent files from scattered across the hard drive.
- Do not record across a network. Copy the desired files to your local hard drive.
- Log out of any networks if possible, including Windows for Workgroups and/or Microsoft Network.
- For best results use SCSI 2 source devices.
- Disc to disc copying, requires a SCSI 2, fully ASPI-compliant CD-ROM drive. We recommend at least a 4x. Copying audio requires a source CD-ROM drive which supports digital audio extraction.
- Make sure your hard drive does Smart Thermal Recalibration. (that is, that it won't recalibrate if the CPU is being used).
- Record at a slower speed.
- Write an .ISO image to the hard disk first, if you have enough hard drive space
- In any operating system, always using the newest drivers from your SCSI controller card manufacturer.
- Always set audio to write at 1x.
- Keep the CDs, the recorder, and your source CD-ROM drive free.
- Make sure your SCSI controller card is FULLY ASPI-compliant.
- Do not try to copy empty directories, zero byte files, or files that may be in use by the system at the time.
- More than 10,000 very small files should be written to an .ISO image first or recorded at 1x if possible.
- Source files need to be in the best shape possible, preferably not too old, no missing bits or data.
- The temporary directory should always have space free at least twice the size of the largest file you are recording.
- The entire computer, from the motherboard bus to the recorder itself, needs to be configured properly for faster recording and highest maximum sync transfer rate.
- Change the DMA transfer rate for the card being used.
- Try increasing the bus clock speed to 8 MHz if the motherboard allows this.
- With DOS 6.22 or below and a source hard disk 1 gigabyte or larger, partitions should be kept smaller than one gigabyte so that hard disk sector size is 16kb instead of 32kb.
- Try a different hard disk and /or gold recordable disc.
Windows 95 Settings
Virtual Memory (if you have more than 16 MB of RAM)
- Right click on My Computer.
- Select the Performance tab.
- Click on the Virtual Memory button.
If you have:
- 8-bit color, select 16MBs for both the minimum and maximum size
- 16-bit color, select 16MBs for both the minimum and maximum size
- 24-bit color, select 32 MBs for both the minimum and maximum size
- 32-bit color, select 32 MBs for both the minimum and maximum size
Hard Drive Typical Role (if you have more than 16 MB of RAM)
- Right click on My Computer.
- Select the Performance tab.
- Click on the File System button.
- Choose the Hard Disk tab.
- Change "Typical Role of this machine" to Network Server. This re-prioritizes the hard drive so that it is given priority over other hardware and software functions
Turning Off Auto Insert Notification
Note: You should do this for every CD unit on your SCSI bus, including the CD recorder itself!
- Right-click the My Computer icon on the desktop.
- Select Properties from the menu. The System Properties dialog box opens.
- Click the Device Manager tab.
- Click the plus sign next to the CD-ROM icon until you see the name of your CD drive. Select it.
- Click on the Properties button. The Properties dialog box for your CD drive will open.
- Click on the Settings tab.
- Deselect "Auto insert notification."
- Restart your system as prompted.