Breaking the 15 partitions barrier

Has anyone been able to break the 15 partitions barrier for scsi disks?
I have a Vostro1500 running Kanotix and I have this insane need for more than 15 partitions: 4 primary go off for Dell diag, Recovery, Vista and the extended partitition
Then I have 4 more parts for two linux system (2 /, 1 /home, 1 swap)
2 partitions for Windows OS data and my documents; more partitions for applications and data (I like to keep them in separate partitions for easy cloning) and when it comes for the ext3 data partition I've already run out of the allowabel partitions for a scsi disk. (What If I wanted a /usr and a /home for every linux distro?)

I've read that this is an arbitrary limit (something of the sort "640 kB will suffice...) and that it is possible to ovverride.
Anyone have succeeded in doing this?

Envelope pushers , talk to me!

 

I thought that is a kernel limitation ? There is some discussion going on about it lately.

Though I am wondering why not just use LVM ? Sure Windows may not like it but I believe it should be possible to reduce it to 3-4 partitions, say 2 for Windows, 2 for linux where one of them being the boot partition.

Almost all distro and live CD nowadays supports LVM so rescue/backup etc. should not be an issue. Not sure about the Windows side though but who would need Windows disk management tools for linux content ;-)

 

It's a bios limitation from what I know. EFI systems (Mac's, primarily) don't have the problem.

 

If you mean primary partition, it may be the case. However, I don't think that is the case when the partitions are sitting inside an 'extended' partition where theoretically it can be any number. The mentioned limit as far as I know is a limitation of the scsi driver in linux.

 

Well, as far as I know, the structure inside extended partitions is the same. You just pretend that's a whole harddrive, so it gets another four partitions. As far as I know. Not 100% sure though.

 

No, chimpanzee is right: the limitation is only in Linux and it is arbitrarily imposed. The data for a logical partition in an extendend partition is 'chained' in the sense that each partition contains the starting sector of the next partition.

Besides, Windows allows me to have as many partitions as the letters of the alphabet. So it couldn't possibly be a bios limitation.

I had read an article on a linux-oriented magazine about a patch to remove this limitation but I can't seem to find it again. I wanted to know if someohe tried to patch the kernel and if there are side effects I should be aware of.

 

The 15-barrier limit only affects linux while using SCSI. I believe IDE allows 63 max partitions. It seems to cap it at 15 luns per controller to seemingly keep the harddrive from over-working itself to death (at least I believe that).

I've seen people bypass it in linux, but I don't remember off the top of my head how they went about it. I'll see if I can dig a little deeper for ya though.

 

On one harddrive? Or in total?

 

15 partitions?! Wow, that's a lot.

 

On one drive.
In fact I realized the limit in Linux when, after creating four more partitions in Windows Vista, I got an error message at the next Linux boot.
Linux was not able to read the last three NTFS partitions, and it was not possible to create the five more ext3 partitions I wanted.

I could create the ext3 partitions before the 15 partitions limiti, so that it would not be possible to access to the last NTFS volumes only (I have a FAT32 exchange area so that would not be a major problem); but it'd be nice to be able to overcome that limit.

On my desktop I have 4 hard disks with some 40 partitions, 24 of which are FAT32, the rest are ext3 partitions for Linux. Funny thing is that in that case I was limited by Windows 26 partitions limit, while I did not even get close to the 63 partitions limit per hard disk for Linux EIDE disks.

Murphy's law at work, no doubt.

 

Naaaaa, not if you have a multiboot system. Consider 2 windows, 3 or 4 linux, each with its own / and /home partitions; if you want to decouple the OS, the OS data, the programs, the programs' data and your data it's easy to get over that limit.

 

Because I did not know what it was .
Sounds interesting. But then, the reason I am using more partitions is that I want to make sure that if something goes wrong on one partition I could still count on the other ones being left intact.
This LMV thing seems to me (but I've read too little to have an informed opinion at this point) like putting all my eggs in one basket.
I need some reading before even considering such an option.

I've read something about devicemap that could solve my problem. The links are on the laptop,though. Aw there must be an easy way out, for Tux's sake!

 

LVM is kind of 'extended extended partition' and it use device mapper. From linux's perspective, each logical volume is a 'partition'. The only difference is that they can be shrinked/extended at will and can be across multiple HD or partition or even over the net.

In a sense, just another level of indirection.

NT(i.e. all NT based Windows including Vista) has similar feature too but not frequently mentioned.

Unfortunately, unlike partition, they cannot be shared among Windows and Linux or other OS.

 

It seems there could be a way out. Not by breaking the 15 partition limit for scsi disks but by seeing the SATA drive as IDE and not SCSI.
I'll start a new thread since it's a completely different subject.