Random missing /dev entries for hard drives / udev problem ?

[Alan AZZERA]

Hello.

I'm facing a weird problem : yesterday, I could dynamically mount from Nautilus a partition who was not present in /etc/fstab. Today it's not possible anymore. The HDD is correctly detected (/dev/sdd), parted or cfdisk say ther is only 1 partition (that is correct), but when I try to mount /dev/sdd1 from command line, I get ther error "mount: périphérique spécial /dev/sdd1 n'existe pas" (in US : "special device /dev/sdd1 does not exist").

I also ran into another weird problem last weekend, while installing Ubuntu 11.04 for a new-switching friend of mine. His brand new PC is an Acer Aspire X3910. Its hard drive is alternately detected as /dev/sda and /dev/sdc. It's not a big deal for daily use, but hardware monitoring tools such as hddtemp report rogue temperature (and for a good reason : try to read information from a non existent /dev entry !)

These 2 problems lead me to imagine that there could be a problem with UDEV. I tried to write a static udev rule to fix the second issue, but I did not succeed (I'm quite a newbie for these sorts of thing !) If you, dear reader, are able to help me right now, feel free to do so and be greatly thanked in advance !

Anyway, thanks a lot for reading AND producing a great system. I do prefer to face such difficulties than struggling with Windows !

Best regards,

Al.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: udev 167-0ubuntu3
ProcVersionSignature: Ubuntu 2.6.38-11.48-generic 2.6.38.8
Uname: Linux 2.6.38-11-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
CustomUdevRuleFiles: 10-vboxdrv.rules
Date: Wed Sep 14 14:01:24 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
MachineType: Dell Inc. OptiPlex 755
ProcEnviron:
 LANGUAGE=fr_FR:en
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-11-generic root=UUID=12948e11-71e0-4956-9a9d-5b32539fa1f8 ro quiet splash vt.handoff=7
SourcePackage: udev
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/30/2008
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A10
dmi.board.name: 0GM819
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 6
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA10:bd04/30/2008:svnDellInc.:pnOptiPlex755:pvr:rvnDellInc.:rn0GM819:rvr:cvnDellInc.:ct6:cvr:
dmi.product.name: OptiPlex 755
dmi.sys.vendor: Dell Inc.

[Brian Murray (brian-murray)]

The issue with using /dev/ entries for mounting disks is that they can and do change. Instead one should be using UUIDs as documented here https://help.ubuntu.com/community/UsingUUID.

[Alan AZZERA (azzera-alan)]

Dear Mr. Murray,

thanks for your answer. But did you read carefully my post ?

I have 2 problems that seems possibily related to me :
* one action that used to be efficient is not any more, and I cannot understand why a HDD conveniently detected (as /dev/sdd) doesn not have its partition accessible in the same way. I have never see this behavior before, from Ubuntu 6.06 to 10.10, and Debian 3.0 to 6.0. If this way of access is deprecated, it should be completely prevented, not just incompletely. That sounds really weird ;
* AND the other problem, with changing /dev/ entries which cause trouble to hddtemp and the udisk probe (letting the Gnome panel temperature applet report incorrect values for HDD). There must be a way to fix these /dev entries, but I'm not enough skilled to find it alone. And one more time, that used to work perfectly in earlier versions of Ubuntu. Now, same actions lead to incorrect results.

Thanks for your time & help. Best regards,

Al