The case against LVM
Gene Heskett
gene.heskett at verizon.net
Fri Aug 10 04:06:34 UTC 2007
On Thursday 09 August 2007, Rick Stevens wrote:
>On Thu, 2007-08-09 at 18:58 -0500, Mikkel L. Ellertson wrote:
>> Robert P. J. Day wrote:
>> > On Thu, 9 Aug 2007, Rick Stevens wrote:
>> >> Uhm, not exactly. You get up to four primary partitions, one of which
>> >> can be an extended partition. Inside that extended partition you can
>> >> have as many "logical" partitions as you wish.
>> >
>> > i'm not convinced of that infinite limit:
>> >
>> > http://www.justlinux.com/forum/showthread.php?threadid=150073
>> >
>> > anyone want to clarify that?
>>
>> From what I understand, there are a max of 16 device entries created
>> for a SCSI hard drive. (sdx and sdx1 through sdx15) So while you can
>> have more partitions then that, Linux will not let you access them
>> when using the SCSI code to access the drive. I believe it is a
>> driver problem more then a udev problem.
>
>Well, the "x" in your example can take the RE form "[a-z]+". For
>example, we have some storage arrays with, oh, 130 LUNs on them. They
>appear as /dev/sda[1-15] through /dev/sdiv[1-15]
>
>As far as the partition numbers, that's based on the minor number of the
>block device. The formula is "(16 * drive number) + partition number".
>The "16" is what limits it to 16 partitions (with partition 0 being the
>same as the whole drive, e.g. "/dev/sda0" is the same as "/dev/sda").
>
>"man sd" will show you the magic.
not on my uptodate FC6 install Rick. That manpage has a quite Jurassic 1992
date, and there is no way one can infer what you just wrote from that
documents contents.
---------Bottom of file----------
FILES
/dev/sd[a-h]: the whole device
/dev/sd[a-h][0-8]: individual block partitions
1992-12-17 SD(4)
---------
If this document isn't correct, it should be made so. I don't see any way out
of sda16 not being equal to sdb0, and sda17 then = sdb1, eg the next device's
first partition, (if its not an outright error) using the logic described in
this file.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
A clever prophet makes sure of the event first.
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