devfs und SCSI Partitionsbegrenzung

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sentor

devfs und SCSI Partitionsbegrenzung

#1 Post by sentor »

Hallo Community,

weiss jemand, ob die Partitionsbegrenzung von SCSI PLatten, die aufgrund der major und minor Vergabe für Devices da ist im devfs aufgehoben ist und hat jemand mit dieser Art von Filesystem schon erste Erfahrungen gesammelt?

Besten Dank für Informationen.

sentor

wurstel

Re: devfs und SCSI Partitionsbegrenzung

#2 Post by wurstel »

Ich glaube, dass das devfs nicht zur Aufhebung der Begrenzung führt

Descartes

Re: devfs und SCSI Partitionsbegrenzung

#3 Post by Descartes »

<blockquote><hr>
6.3 PC Disk Limitations

The PC BIOS generally adds additional constraints for disk partitioning. There is a limit to how many ``primary'' and ``logical'' partitions a drive can contain. Additionally, with pre 1994-98 BIOS, there are limits to where on the drive the BIOS can boot from. More information can be found in the Linux Partition HOWTO and the Phoenix BIOS FAQ, but this section will include a brief overview to help you plan most situations.

``Primary'' partitions are the original partitioning scheme for PC disks. However, there can only be four of them. To get past this limitation, ``extended'' and ``logical'' partitions were invented. By setting one of your primary partitions as an extended partition, you can subdivide all the space allocated to that partition into logical partitions. You can create up to 60 logical partitions per extended partition; however, you can only have one extended partition per drive.

Linux limits the partitions per drive to 15 partitions for SCSI disks (3 usable primary partitions, 12 logical partitions), and 63 partitions on an IDE drive (3 usable primary partitions, 60 logical partitions). However the normal Debian GNU/Linux system provides only 20 devices for partitions, so you may not install on partitions higher than 20 unless you first manually create devices for those partitions.

Quelle: <a href="http://www.de.debian.org/releases/stabl ... .html#s6.3" target="_blank"><!--auto-->http://www.de.debian.org/releases/stabl ... <!--auto-->
<hr></blockquote>

<blockquote><hr>
In <349B306B.259E@cc.wwu.edu>, Wes Taylor <n9335589@cc.wwu.edu> writes:
> I want to add Linux to my computer. My single hard drive currently has
> Boot Manager, a primary partiton for booting OS/2 in HPFS format, an
> extended partition for a FAT and a second HPFS logical drive, and a
> primary partition set aside for Linux. The installation documentation
> (Redhat 5) strongly recommends multiple partitions for Linux. As far as
> I can tell, I cannot subdivide a primary partition into more
> partitions.

I try to provide a generic answer. The main partition table has 4 entries.
To overcome partition number limitation the extended partition type was
agreed. Extended partition is just a container for logical partitions. Logical
partition tables specify one logical partition and a link to next logical
partition table, thus forming a linked list of logical partition tables. In
theory there is no limit for logical partitions, but dos, OS/2 and NT can
handle only 24 hard disk partitions. Linux has some limit per disk, but
many distributions include block special device files only for 16 or 20,
the rest you must make yourself.

Quelle: <a href="http://groups.google.com/groups?meta=hl ... 1%40rk2.rk" target="_blank"><!--auto-->http://groups.google.com/groups?meta=hl ... <!--auto-->
<hr></blockquote>

<blockquote><hr>
> Yet using Linux fdisk I discovered that I can create only 7,
> that is only one extended partition. Is it true, or I missed
> something. (I used redhat installation disk to run fdisk).
>
You have two choices:
1) You can have up to four and only four primary partitions.

2) Or you can have up to three primary partitions and one
extended partition. Within the extended partition you can
create as many logical drives (partitions realy) as you
want. I am aware of no limit.

Quelle: <a href="http://groups.google.com/groups?selm=38 ... put=gplain" target="_blank"><!--auto-->http://groups.google.com/groups?selm=38 ... <!--auto-->
<hr></blockquote>

<blockquote><hr>
> How do you know which numbers to start from and which numbers to end at
> when you are creating partitions on Fdisk?

Start with 1 increase sequentially. Doing it any other way may confuse
the system. Did I ever tell you about how Linux's fdisk and MS's fdisk
got into confusion and how I accidentally deleted partitions I wanted to
keep but survived through using quick wit and cunning?

You can only have 4 primary partitions (/dev/hda1 through /dev/hda4). You
can have extended partitions (/dev/hda5 through /dev/hda16) if you
sacrifice one primary partition (see above -- my /dev/hda4 has been
sacrificed so I can have /dev/hda5 and /dev/hda6). The reason for this
rule is because initially Microsoft made an oversight that people
probably wouldn't want more than 4 partitions... then they changed their
minds and decided to add extended partitions, which we now make use of
under the Linux world for happily goodness.

Quelle: <a href="http://www.lugod.org/mailinglists/archi ... 00022.html" target="_blank"><!--auto-->http://www.lugod.org/mailinglists/archi ... <!--auto-->
<hr></blockquote>

<blockquote><hr>
The disk partitions are also sequentially numbered. The first partition has the number 1, so sda1 would be the first partition on the first SCSI hard disk. When dealing with primary and extended partitions, however, the numbering gets a little confusing. The four possible primary partitions (on Intel 386-based machines) are numbered 1-4. The logical partitions are numbered 5-15. (Yes, you can have that many). Regardless of how many primary partitions you have, the logical partitions are always numbered starting with 5. For example, if you have one primary partition and one extended partition that contains a single logical partition, you would access these partitions using the device nodes/dev/hda1 and /dev/hda5, respectively.

Quelle: <a href="http://www.linux-mag.com/1999-10/guru_01.html" target="_blank"><!--auto-->http://www.linux-mag.com/1999-10/guru_0 ... <!--auto-->
<hr></blockquote>

sentor

Re: devfs und SCSI Partitionsbegrenzung

#4 Post by sentor »

Aufhebung der Beschränkung durch einen LVM. Auch devfs müsste gehen, indem man die Bloock-IO Layer fixt. Aber keine Ahnung was da zu machen ist, deshalb habe ich mir mit den LVM geholfen.

Gruss sentor

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