Re: Partitioning on i386

[Jon Fullmer <jon@jonfullmer.com>]

First, I was mistaken. It's actually a maximum of 15 partitions for a SCSI
drive and a maximum of 63 partitions for IDE.  I apologize for not verifying
my response.  I had run into this issue before, and I remembered that IDE
drives allowed for a lot more partitions, but I couldn't remember the
maximum (I knew that the SCSI limit was correct).

Next, RTFM?  Good advice!  Here's an excerpt from the Partition HowTO
(http://www.tldp.org/HOWTO/Partition/partition-3.html):

"The primary partition used to house the logical partitions is called an
extended partition and it has its own file system type (0x05). Unlike
primary partitions, logical partitions must be contiguous. Each logical
partition contains a pointer to the next logical partition, which implies
that the number of logical partitions is unlimited. However, linux imposes
limits on the total number of any type of prtition on a drive, so this
effectively limits the number of logical partitions. This is at most 15
partitions total on an SCSI disk and 63 total on an IDE disk."

I ran into this issue over a year ago when I tried to create more than 15
partitions on a SCSI drive and kept getting mysterious failures. From my
research back then, it seemed that I also discovered this limitation to be
unique to the Intel platform (which makes sense, as other platforms aren't
bound to the primary/extended partition set up), but I've never proven that
one way or the other yet.  That, and the HowTO entry I quoted would seem to
designate this limitation as unique to Linux, not the platform.

Anyway, I hope that helps.  As I've mentioned, I've hit the 15-partition
SCSI ceiling before, but I would think you'd be pretty safe with IDE.  It's
hard to imagine setting up more than 63 partitions on a single drive.  But
then, with 256 GB drives....

 - Jon

on 8/8/03 2:53 AM, Scott Taylor at scott@dctchambers.com wrote:

> Jon Fullmer said:
> 
>> I believe you are correct, Andrew, when dealing with SCSI drives.  But
>> (if
>> I'm not mistaken) with IDE drives, the maximum is 40 total partitions
>> (3
>> primary 1 extended 37 logical).
> 
> man fdisk
> 
> RTFM
> 
> It has nothing to do with SCSI or IDE, only primary partitions are
> limited.  Most Linux installs allow for 37 partitions by making nodes
> /dev/hd?0 - /dev/hd?36.  Doesn't mean you can't create more.
> 
> 
> 
> 
> --
> Scott
> long .signature files are annoying
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