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Old 09-11-2009, 02:36 PM   #1
evans52
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Max number of logical Partition.


Hello, Everybody,
I'd just like to know the max number of logical partitions an extended partition can hold. Is that number different for IDE and SCSI hard drives? Thank you so much!
 
Old 09-11-2009, 02:58 PM   #2
rayfordj
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max partitions: SCSI is 15; IDE is more, but on RHEL they [loosely] hold you to 15

1 - pri
2 - pri
3 - pri
4 - ext
5 - log
6 - log
...

Last edited by rayfordj; 09-11-2009 at 03:00 PM.
 
Old 09-11-2009, 03:04 PM   #3
knudfl
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With a maximum of fifteen partitions total for Linux :

4 primary's ( number 4 is the extended, holding 'logical's )

makes the count of logical's = 11.
 
Old 09-11-2009, 03:37 PM   #4
i92guboj
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Last time I checked it was 64 device nodes per disk for regular drives, and 16 for scsi, leaving out the node for the device itself, that's 63 partitions for ide and 15 for scsi, 1-4 are reserved for primary partitions regardless if they exist or not (or extended, which is the same), the rest for logical drives.

This is entirely OS dependent however. There's nothing in the hardware stopping you from defining 400 partitions.
 
Old 09-11-2009, 06:47 PM   #5
syg00
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By "regular" I assume you mean IDE. This was certainly true prior to the libata change - after that even IDE became (software) constrained to 15 as well.
There was some (plenty) of grumbling about this at the time - there was mutterings from the kernel devs to "fix" this, but I've never bother checking if it came to pass.
 
Old 09-11-2009, 06:51 PM   #6
i92guboj
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Yes. I meant IDE (the old IDE). All the SATA drives, just like USB and most storage devices nowadays go though SCSI, even the IDE drives go now through the SATA/PATA interface, so nowadays that would be 15, unless you are using the old IDE drivers. But, as you, it's been long since I checked. So there's the slight chance that this have changed since then.

It doesn't really bothers me, 15 partitions in a single disk are way above my requirements, I'd rather spend bucks in another drive.
 
Old 09-14-2009, 12:23 PM   #7
evans52
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Thank you for your responses! Please excuse my ignorance, but I have one more question. Would the naming scheme for an IDE partition table be as followed (to follow up on what rayfordj said above)? Thank you again!

hda1 - primary
hda2 - primary
hda3 - primary
hda4 - extended
hda5 - logical
hda6 - logical
hda7 - logical
hda8 - logical
..
hda13 - logical
hda14 - logical
hda15 - logical
 
Old 09-14-2009, 12:43 PM   #8
i92guboj
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Yes. Though you could just as well have:

Code:
hda1 (extended)
hda5 (logical)
[...]
hda15 (logical)
 
Old 09-14-2009, 11:50 PM   #9
Smartpatrol
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...

Last edited by Smartpatrol; 03-11-2010 at 10:25 PM.
 
Old 09-15-2009, 09:13 AM   #10
catkin
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BING (Boot It NG), an excellent boot and partition manager has the ability to create "more than 200" (= 256?) primaries. I have no connection with the company except that I used to use BING extensively.
 
Old 09-15-2009, 11:31 AM   #11
i92guboj
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Quote:
Originally Posted by catkin View Post
BING (Boot It NG), an excellent boot and partition manager has the ability to create "more than 200" (= 256?) primaries. I have no connection with the company except that I used to use BING extensively.
More than four primaries is simply impossible if you want to retain MBR compatibility, which is what most OSes use and understand. There simply isn't any more space into the MBR to reference more than four partitions (64 bytes, from 446 to 510).

The rest of partitions are defined into secondary boot records, that's the way to have more than four partitions without screwing the mbr standard.

I am not familiar with that program, but if it does indeed create 200 primary partitions, then there's no way that it can be compatible with the 512 bytes mbr model that most OSes use nowadays.

If you meant 200 partitions that are not necessarily primary then it's ok. You can have as many logical partitions as you need. As said, the above limits are completely arbitrary and OS dependant, Technically nothing stops you from having 200 logical drives.
 
Old 09-15-2009, 11:49 AM   #12
saikee
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How about 126?

They can be created in less than a minute too, by a simple Bash script.

I tried it by putting Xp repeatedly in 126 logical partitions and was able to boot everyone. So it works. sfdisk can be used to create 130 partitions (4 primaries and 126 logicals).

The downside

Not every partitioning tool in Linux can cope with it!

As far as I know there is no limit in the kernel or the boot loaders. The limit depends on what the partitioning tool can come up with. So far I have found

fdisk - will not display beyond 60 partitions
cfdisk - maximum 63 partitions
sfdisk - can do 130 partitions
gparted - beyond 130 partitions.

Another link with additional information.
--------------------------------------------------------------

On the argument of 256 primary partition I believe this is just a proprietary software written as a management layer between the OS and the Bios. Don't think it is compatible with all the PC systems. I believe it works as specialised boot loader by arranging the partition table in a non-standard way that only that proprietary software can read/write.

Last edited by saikee; 09-15-2009 at 12:07 PM.
 
  


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