An idea that *might* make Knoppix run faster (or maybe not)

[rigurat]

What if I burned the CD ISO of Knoppix on a DVD instead of a CD? I mean if the boot loader would be on the first part of the DVD, then a bunch of empty data on the DVD (80% maybe, between the boot loader and the real data) and the rest of the real Knoppix data on the end of the DVD disc (which is were the DVD is accessed the fastest). Then I load it on a regular 16x DVD drive (not a DVD+-r/rw). Would that make it faster? Because I hear that a 16x DVD drive can read at 22 mb/s while a 52x CD read is at 7.8 mb/s.

[tearinghairout]

My guess is that this will not make much difference to the speed.

The limiting factor of most disks in general is not how quickly it reads the data off the disk, but how much time it has to spend moving the read head back and forth and adjusting the speed of the disk and then waiting for the right bit of data to arrive under the read head.

This is why most hard drives specifications quote firstly the "access time", usually in milliseconds, and also the speed in terms of RPM.

On CD and DVD drives, these are very slow.

Also, I believe most CD and DVD drives actually stop the disk after a short period of inactivity (I think only a period of seconds) so the disk needs to be actually spun up to speed repeatedly, and that is probably the slowest thing of all.

However, I would be most happy to be proven wrong.

[rigurat]

I haven't tried yet, mainly because I can't! I don't know how to just modify a CD ISO were I just insert lots of empty space (a bunch of 0's) between the boot loader and the Knoppix DATA until it's expanded to a 4.7 DVD ISO out of that and then burn it to a DVD disc. Since most of it is empty space, I'm very sure it will compress nicely into a 700mb .zip file.

[Bernd Blaauw]

Burn the ISO to the DVD, without any blank space.

it should still use DVD speeds, instead of cdrom.

In theory I can test the DVD-speed of my DVDwriter and reader by creating a 800MB ramdisk and then copying the KNOPPIX file to it (one single large file)

this is because I have 1GB RAM.

same trick can be achived with the KNOPPIX toram option, as long as your DVD is also only 700MB or so (this is a bug, Knoppix toram cheatcode copies everything to the ramdisk, not just the knoppix image..and I don't have 4.5GB RAM!)

happy testing,

Bernd

[zurk]

What if I burned the CD ISO of Knoppix on a DVD instead of a CD? I mean if the boot loader would be on the first part of the DVD, then a bunch of empty data on the DVD (80% maybe, between the boot loader and the real data) and the rest of the real Knoppix data on the end of the DVD disc (which is were the DVD is accessed the fastest). Then I load it on a regular 16x DVD drive (not a DVD+-r/rw). Would that make it faster? Because I hear that a 16x DVD drive can read at 22 mb/s while a 52x CD read is at 7.8 mb/s.

why dont you just use UDF and write the entire thing directly to dvd ? no compression and the UDF filesystem botos nicely very very fast with no remastering overhead. unless of course you have 9GB of stuff you want to fit on a 4.5GB DVD.

[Ghandalfar]

zurk: bad idea. You actually get faster loading times with compressed knoppix because it doesn't have to read as much. CPU is faster then reading from UDF