What are the main causes of Bufferunder run?

Fabritzo

I've tried to write a cd 4 times now...wasting 2 then had 2 simulation failures....this is the first time I've had this recurring problem.

Saruman

Try Google.. it holds all your answers.. but really come on!! The only real reason you are getting them is because you dont have a burner with BURN proof etc... Go buy one..., its only going to cost you about €70

Silent Bob

Buffer under-run is when the write buffer for the CD-burner empties.

It depends on the size of the buffer obviously but should *not* happen if you are writing to CD from HD.

A HD should have a sustainable transfer speed in the region of 66-133MB/s (assuming you have a UDMA drive). This is WAY faster than a CD burner can burn (an 8x burner is buring at about 1.2 MB/s).

If you are doing a CD-to-CD copy than it could be that your reader isn't fast enough to keep up with the burner.

Dropping record speed will reduce the possibility of buffer under-run, in this case.

As far as keeping the CPU mostly free to deal with the burning goes, I don't really know. I have heard anecdotal evidence of people reompiling their OS kernel while burning CDs and not encountering any trouble.

Since every modern machine has an I/O controller and DMA controllers etc. the CPU has very little work to do when it comes to transferring data between I/O devices and main memory.

It sounds more like dodgy drivers really...

Raz

Another problem (which cost me countless CDs before I copped on!) is if you are copying from CD to CD and the source CD is damaged ie. scrapes following the track of the laser or scrapes on the label side, then the reading CD drive will keep trying to get this information and the buffer of the CD writer will empty while it's doing this.

The other reason I've lost countless CDs is due to the fact that the CD burner I have is rubbish anyway! I lost 11 discs out of a 20 pack before I got a decent copy of anything!!

Anyway, if you're determined to get the CD written (which you seem to be considering the amount of attempts) then set the burner to it's lowest burn speed, and set the reader to the same speed (Nero lets you do this)

Best of luck

quozl

having the source and the destination drives on the same ide channel (ie master and slave on the same cable) is a common cause of underuns.

The ide system can't quickly switch from read to write and back again, so if you're doing both on the same channel you get a fraction of the throughput. So make sure you're using seperate channels.

and incidently, udma133 drives have a throughput of more like 45MB not 133.

Greg

Captain Trips

Can I ask how many CDs (estimate) you have burned on it, and have you been overburning many?

That totally feckered a 4x Philips of mine after around 150-200 CDs. Estimated running time of these burners is only around 900 hours any (so you'd get maybe 6-700 CD burned, but less if you've been overburning).

I ended up not being able to complete a burn on any burn I tried.

Fabritzo

I got it to work by turning the speed down to 4x, as far as I can make out the mp3s were crap-ily encoded and it took too long to turn them in cda....but they are on the same ide, I don't do any overburning and I think I'd say I've burned about 100 cd's with it.

Dalamar

Try using nero to write a cd-image first, then burn the image to the cd, this is slightly better than writing 'on the fly'. Lower write speed, avoid mechanical shock, i.e. don't kick the pc, avoid programs that use the cd drives such as IsoBuster. Avoid converting mp3 -> wav on something less than a 233 mega-hertz P2.

SouperComputer

what are the specs on your machine?

A HD should have a sustainable transfer speed in the region of 66-133MB/s (assuming you have a UDMA drive). This is WAY faster than a CD burner can burn (an 8x burner is buring at about 1.2 MB/s).

[rant] erm, no even the latest SATA drive maxs out at 50Mbs! (roughly!). 133Mbs is the theroetical BW of the bus, and thats debatable if the bus can even do that. Kinda funny the some way people insist on an ATA133 drive when a 120 WD (ATA 100)special will wipe the floor with it!

sheggin marketing people! [/rant]

Silent Bob

Originally posted by SouperComputer
what are the specs on your machine?



[rant] erm, no even the latest SATA drive maxs out at 50Mbs! (roughly!). 133Mbs is the theroetical BW of the bus, and thats debatable if the bus can even do that. Kinda funny the some way people insist on an ATA133 drive when a 120 WD (ATA 100)special will wipe the floor with it!

sheggin marketing people! [/rant]

meh was fairly sure it was lower too, rememberiing hdparm tests of about 40ish MB/s, but I checked out manufacturers blurb before posting, last time I'll believe 'em

Nonetheless my point is valid, HD transfer speeds are way above CD writing speeds.

Typedef

If you are reading files from a FAT32 partition then the most likely cause of a buffer under run error is in fact fragmentation of the file system you are reading from.

Thus, defragment the FS and go burn your warez.