At Fri, 1 Apr 2011 11:05:35 +0100 CentOS mailing list centos@centos.org wrote:
The reason for the udev hotplug rule is simply for the purpose of mounting removable devices as read-only. If udev is left to its devices, everything plugged up is read-write which is verboten in this application. Unfortunately, there seems to be no way (i've found) to distinguish, at device/bus level, between a system HDD, a hardware RAID volume and an eSATA device and handle the eSATA device uniquely from others. All eSATA and USB devices _must_ mount read-only. If everything is lined up at boot, sda and sdb are camped via fstab and udev deals with sdc and above, mounting what are known to be removable devices as r/o. Shotgun, i know, but there is no way of knowing in advance what devices the system (er, appliance) will see.
tangled, huh?
Does this give you a clue (this is a rule I use for my thumb drive, which is a vfat file system, and thus cannot have a LABEL'd file system):
gollum.deepsoft.com% cat /etc/udev/rules.d/10-local.rules KERNEL=="sd[a-z]*", BUS=="scsi", SYSFS{device/vendor}=="Kingston", NAME="thumb"
Hint: the 'brand' of thumb drive I have is Kingston and == can be replaced with !=.
In your special mount read-only hot plug rule, you just need a SYSFS{device/vendor}!="3ware" (or whatever the vendor of the RAID array shows up as -- look in /sys/block/sd<mumble>/device/vendor)
thanks
- csawyer
Robert Heller heller at deepsoft.com Thu Mar 31 14:20:55 EDT 2011
Previous message: [CentOS] CentOS Digest, Vol 74, Issue 31 Next message: [CentOS] figuring out LogVol details for mount Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]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.
- cal sawyer
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