[CentOS] CentOS Digest, Vol 74, Issue 31

Thu Mar 31 18:20:55 UTC 2011

At Thu, 31 Mar 2011 18:23:00 +0100 CentOS mailing list <centos at centos.org> wrote:

> 
> thanks for the reply, Phil
> 
> It would, were udev not inserting USB and/or eSATA drives at /dev/sdb1
> and/or /dev/sdc1 and exposing the array to the udev rule intended to
> handle only removable devices (at sdc or sdd).  The array then mounts
> unpredictably in /media/xxx-sdc1 or sdd1 - not what is wanted - depend
> on how many removable devices are plugged at the time of rebooting. Of
> course, a single removable device will camp at sdb, which is out of
> reach of udev so the whole hotplug thing is broken until someone removes
> all of the devices at site, allowing a clean boot. 

Do you have some *nonstandard* udev rule for hot plug devices? The
*standard* hotplug udev rules are not tied to specific ranges of sdXX's
-- my IDE-based laptop will properly handle a hot plugged USB device at
/dev/sda for example.

The hot plug logic should also not mess with not hot pluged devices.  If
your RAID array is mounted in /etc/fstab (or has a 'noauto' line in
/etc/fstab with the idea of mounting it manually later or has something
in automount's config for automounting it), the hot plug system should
not touch it, no matter what /dev/sdXX it happens to land at, so long as
you are using volume labels or some such to reference the mountable
volumes. 

> 
> mapper correctly places the / filesystem higher in position in
> rc.sysinit, followed by start_udev (where the damage gets done) and
> finally fstab evaluation way down the line.  I suppose i could just
> hardwire the array mount into rc.sysint to engage after modules get
> loaded and hopefully before start_udev, unless there is a better way to
> enforce it.  I'm not sure at this stage (need to analyse that ~1000-line
> script) if there is a suitable insertion point.  It would be really good
> if it could be done outside of rc.sysint in some predictable place.

It *sounds* like you have something non-standard / fishy going on in
udev's rules -- I suspect you have some sort of funky homegrown rule
somewhere. 

> 
> We're "stuck" (but not unhappily) with this kernel/rev for the
> foreseeable future - i have over 100 of these systems and they are
> housed behind VPN'd networks, which mitigates somewhat their inevitable
> vulnerabilities. 
> 
> regards,
> 
> - csawyer
> 
> 
>   30. Re: Controlling the order of /dev/sdX devices? (Phil Schaffner)
> CentOS 5.4(final) 2.6.18-164el5PAE.  I am trying to prevent removable
> USB and eSATA devices from occupying /dev/sdX devices ahead of a 3ware
> RAID controller.  For example: at boot, if a USB drive and eSATA HDD
> (connected to an LSI 1068E onboard controller, reflashed in "IT" mode to
> handle hotplug devices) were both present, they would occupy devices
> /dev/sdb and /dev/sdc, ahead of the RAID controller which ends up as
> /dev/sdd.  As these are removable devices, they should normally get
> handled by custom udev script looking for adds matching
> KERNEL=="sd[c-z][0-9]" ,SUBSYSTEM=="block", so the volume handled by
> RAID controller gets grabbed by udev but fails to mount and subsequent
> udev plug events fails due the slots left empty below /dev/sdd.  If no
> hotplug devices are present while booting, fstab handles mounting of the
> system and RAID volume:
> 
> SATA system HDD	/dev/VolGroup00/LogVol00 /
> RAID array		LABEL=STORE      /store		## mounts ==
> /dev/sdb1
> 
> I realise this description is kind of a tangle, but i am essentially
> looking for a way to hard-map the 3ware RAID controller to /dev/sdb
> (UUID won't work as there are multiples of this system) before PCI (?)
> enumeration picks up the USB and LSI-managed devices so that udev can
> take care of the device at /dev/sdc and above. I've tried blacklisting
> the mpt and usb-storage modules and short-circuiting SUBSYSTEM=="block"
> devices in 05-udev-early.rules, all with zero or negative effect.
> rc.sysinit doesn't appear to be the right place and that's about as deep
> down as i know how to go.
> 
> cheers,
> 
> cs
> 
> ------------------------------
> 
> Message: 30
> Date: Thu, 31 Mar 2011 10:24:42 -0400
> From: Phil Schaffner <Philip.R.Schaffner at NASA.gov>
> Subject: Re: [CentOS] Controlling the order of /dev/sdX devices?
> To: <centos at centos.org>
> Message-ID: <4D948EAA.2070005 at NASA.gov>
> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed
> 
> Cal Sawyer wrote on 03/31/2011 08:13 AM:
> > Hi
> >
> > CentOS 5.4(final) 2.6.18-164el5PAE.
> 
> I hope you are aware that you are using a very obsolete OS with a lot of
> 
> known (i.e. exploitable) security holes and bugs that have subsequently 
> been fixed.
> 
> ...
> > I realise this description is kind of a tangle
> 
> Indeed.  Why does a line in /etc/fstab like
> 
> LABEL=STORE      /store		ext3	defaults	1 2
> 
> not work?
> 
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>                                                                 

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