Can you do a RAID 0 array with CD-ROM drives

[mrman3k]

Is it possible to put 2 CD-ROM drives in a RAID 0 array. So say you put the same CD in both drives, could you theoretically get higher throughput? If there are any problems with this, could you post what they are, maybe there might be a workaround.

 

[smp]

I don't think that's possible .. at least, I've never heard of it.

 

[John]

Umm, no.

 

[ScrapSilicon]

Originally posted by: John
Umm, no.

to which question..he has two...

Originally posted by: mrman3k
Is it possible to put 2 CD-ROM drives in a RAID 0 array.

that would be yes to question #1..hehe..

So say you put the same CD in both drives, could you theoretically get higher throughput?

that would be question number 2 ..of course that's a no

 

[RSMemphis]

Originally posted by: ScrapSilicon

Originally posted by: John
Umm, no.

to which question..he has two...

Originally posted by: mrman3k
Is it possible to put 2 CD-ROM drives in a RAID 0 array.

that would be yes to question #1..hehe..

So say you put the same CD in both drives, could you theoretically get higher throughput?

that would be question number 2 ..of course that's a no

No, sorry, John was right... It's no for both questions...
You can put them onto a RAID controller, but not as a RAID 0 - RAID 0 needs reformating, and how would you do that with a CD...

You can just use the additional IDE ports. But not as RAID.

So NO!

 

[boyRacer]

 

[ScrapSilicon]

Originally posted by: RSMemphis

Originally posted by: ScrapSilicon

Originally posted by: John
Umm, no.

to which question..he has two...

Originally posted by: mrman3k
Is it possible to put 2 CD-ROM drives in a RAID 0 array.

that would be yes to question #1..hehe..

So say you put the same CD in both drives, could you theoretically get higher throughput?

that would be question number 2 ..of course that's a no

No, sorry, John was right... It's no for both questions...
You can put them onto a RAID controller, but not as a RAID 0 - RAID 0 needs reformating, and how would you do that with a CD...

You can just use the additional IDE ports. But not as RAID.

So NO!

that is the point he could put the CDRom drives in the existing RAID 0 .. just won't be a RAID 0(or any other RAID) that's all in effect put the CDRom drives in..the array would be replaced

 

[bex0rs]

Depending on the application, you could use something like daemon-tools to speed cd/dvd access, and of course the disc image could reside on a raid.

~bex0rs

 

[NeilPeart]

Wow. :disgust: There is no need to complicate a simple issue. A RAID 0 stripes the data of two hard drives. That is physically impossible to do with CD-ROM drives. Also, most (if not all) RAID cards won't even recognize optical drives. The answer is no.

 

[mrzed]

Someone explain how it is impossible please. Data on CD's is written on tracks using moving read/write heads and spinning platters. How exactly different is that?

I agree it's impossible with what's out there now. I doubt it will ever be done, because it would be so freaking difficult, but I can't understand how no-one could seriously re-program the things and use striped CDR or something. What physical barrier is there? Doesn't a RAID controller just divide a data stream into two? Why couldn't you change the firmware in a burner in order to let it work?

 

[mrman3k]

mrzed pinpointed my question exactly. And for the record, I don't have 2 CD-ROM drives, just my friends and I were talking about trying this.

I thought that RAID 0 controllers just split the data into 2 streams and therefore if you have 2 copies of the same CD and put them into both of the 2 CD-ROM drives, then you could do some RAID 0 thing.

 

[Viper GTS]

RAID 0 relies on the fact that each volume has half the data - Thus each device can do consecutive reads at full volume speed, and the two streams are combined into one stream that is roughly double the individual volume speed.

CD-ROMs differ in that both volumes would have ALL the data. You would have to discard every other cluster (or however you broke it up). You would have two devices reading at full speed, but each reading all the data and discarding half. The end result would be the exact same as reading it off one disc - And possibly slower, considering the completely unnecessary processing that would be required to split, then rejoin the data.

Viper GTS

 

[NeilPeart]

Next time phrase your question differently. I thought you had 2 CD-ROMs that you wanted to set up in a RAID 0 right now. How about clarifying by asking WILL it be possible in the future. Viper's answer is basically a solid reason why it is not possible.

 

[Alphazero]

Originally posted by: mrzed
Someone explain how it is impossible please. Data on CD's is written on tracks using moving read/write heads and spinning platters. How exactly different is that?

Optical drives use the ATAPI (Packet Interface), which is incompatible with ATA. CD data is written in one continuous track, and there are certainly no platters. In fact, CD and HD read / write methods are completely different. RAID is simply not an option. Cannot be done, even theoretically.

 

[mrzed]

I'm not arguing, but I don't really get the explanation. Why does CDR inherently need to have all the data? I assumed a RAID0 controller would split the data before it got to the device. How does the CD have all the data if the controller never sends it?

Please go into more detail. How is it physically impossible?

 

[UlricT]

hey... theoretically, it should be possible to format 2 CD-RWs on two drives linked up to be shown as one logical disk. But think about it, you gotta write 2 CDs at the same time to access one. And what if you put in one striped CD with another program CD??? THAT drive is gonna be confused...

I suppose it should be possible, simply extend RAID to ATAPI as well... simple aint it?

 

[BigFatCow]

this might help explain...

just read the raid 0 part...

 

[fyleow]

Originally posted by: mrzed
I'm not arguing, but I don't really get the explanation. Why does CDR inherently need to have all the data? I assumed a RAID0 controller would split the data before it got to the device. How does the CD have all the data if the controller never sends it?

Please go into more detail. How is it physically impossible?

I think they are talking about reading and NOT writing. You can't read twice as fast with CDROMs because in a RAID the data is broken up into two. Each drive reads half of it and combines it into the completed data so it's faster.

I think what mrzed is trying to say is why can't you burn a file into two CDs using a RAID 0 and it will be faster, correct?

 

[JHeiderman]

He said "Can you" not "Could you if you could play make believe and pretend that things would work in ways they don't actually work". The short answer is No. The long answer is N o.

Now.. a bit of trivia for you young'uns. Packard Bell made a 486 back in the day (circa 1995) that had TWO CD-Roms in it. That was completely unheard of back then in a consumer PC. It had a little drive that would spoof the two CD-Roms as one drive. Basicaly, when you put in two discs in the CD-Roms (1 in each) it would handle it as one big disc. It didn't work past Win 3.11 but for it's time it was pretty cool. That was a selling point because a lot of software had two discs and you could put disc 1 and disc 2 in the drives and never have to swap them out.

So, this may be the closest possible thing to what you want to do even though it's something out of the perverbial "stone age" to most of you guys.

- J

 

[mastertech01]

If you just want to try something different you can raid tape drives, like DAT drives.

 

[mrzed]

I know what RAID0 is. I also know it's not possible just to plug it in with a little tweaking and go.

I even know that it's really not a practical concept in any way. Why would you possibly want to do it?

But when someone says it's physically impossible, I get curious why. Nothing so far has explained it ,aside from the "it just doesn't work" and RTFM answers. I simply don't understand why it couldn't be adapted by someone with the knowledge and resources (ie: electronics engineers) to make it work, not that there is any reason to.

 

[Viper GTS]

Originally posted by: mrzed
I know what RAID0 is. I also know it's not possible just to plug it in with a little tweaking and go.

I even know that it's really not a practical concept in any way. Why would you possibly want to do it?

But when someone says it's physically impossible, I get curious why. Nothing so far has explained it ,aside from the "it just doesn't work" and RTFM answers. I simply don't understand why it couldn't be adapted by someone with the knowledge and resources (ie: electronics engineers) to make it work, not that there is any reason to.

If you were to word your question this way:

Could someone, if they so desired, develop a system of optical drives similar to today's CDRW's that could stripe data across multiple discs, and read the data back in the same way?

The answer would be yes.

But you would have to completely abandon existing standards and start over.

Which is what we've been trying to say all along. By saying "CD-ROM" you limit yourself to current standards, the name implies more than just an optical disc.

Viper GTS

 

[Wolfsraider]

Originally posted by: John
Umm, no.

simple and effective

 

[WienerDog]

Originally posted by: Wolfsraider

Originally posted by: John
Umm, no.

simple and effective

It must have been the "umm" that threw everyone off, if you didn't say "Umm" maybe this conversation would not have gotten so difficult.

Viper has it right though: Could someone, if they so desired, develop a system of optical drives similar to today's CDRW's that could stripe data across multiple discs, and read the data back in the same way? Yes

You're not talking RAID 0 though, you aren't talking about existing cards and software, and you definitely aren't talking about plugging a CD-ROM into a RAID controller and getting double speed.

 

[mrzed]

I don't think it really got difficult.

It was actually the "physically impossible" comment that got me wondering. But Viper's answer did finally get to the heart of the matter, which is to say it would be physically possible to stripe the data, but it would not be RAID0 because that implies a certain standard.

I was just under the impression that people were saying it would not be possible at all to stripe optical drives and that didn't seem to make sense.