Hi Ralph
Thanks for all the info, I've just passed both your last emails on to
him and it sounds as if you've found why the fault happens. He will get
back to me with the outcome and if it clears the problem. His set-up is
complicated and that may not be helpful and he's trying to be too clever!!
C A Wills
On 16/01/11 17:09, Ralph Corderoy wrote:
Hi Clive,
The limit to the number of logical partions is OS dependant. For
IDE/SATA disks on Linux I'm pretty sure it's 64.
I think John's right. Three usable primaries, the fourth primary is
the extended one so isn't used directly but can contain up to 60
logical partitions. So the kernel tracks 64 partitions, 63 of which
can contain filesystems.
We've been chatting more about this on #dorset and now think that since
the merger of the IDE and SATA device driver in the kernel, which caused
the renaming of /dev/hda to /dev/sda, a new limitation is in place on
the number of logical partitions that can be accessed on a /dev/sd?
drive.
$ ls -l /dev/sd?
brw-rw---- 1 root disk 8, 0 2010-12-30 16:28 /dev/sda
brw-rw---- 1 root disk 8, 16 2011-01-13 16:32 /dev/sdb
$
The minor device number for each drive goes up in 16s. For /dev/sda,
we've
0 -- whole drive.
1-4 -- primary partitions, one of which may be extended and won't
appear in /dev.
5-15 -- logical partitions.
So the limit is 11 logical partitions. Your friend's error about the
17th partition may be down to 16 minor device numbers already being
taken, i.e. he had 9 logical partitions before he started the install, /
and swap took him to the maximum of 11, and /home then failed.
We also think nine logical partitions is quite a few and are curious as
to why there are so many. :-)
And yes, the hda -> sda migration does mean that drives with lots of
partitions being happily accessed yesterday now can't access some of
those later ones with a new kernel. Complainants are on the Internet.
Plus the Ubuntu install guide would seem to be wrong and out of date.
Cheers,
Ralph.
--
Next meeting: Bournemouth, Tuesday 2011-02-01 20:00
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--
Next meeting: Bournemouth, Tuesday 2011-02-01 20:00
Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/
How to Report Bugs Effectively: http://goo.gl/4Xue
