LinuxQuestions.org
Latest LQ Deal: Latest LQ Deals
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Server
User Name
Password
Linux - Server This forum is for the discussion of Linux Software used in a server related context.

Notices


Reply
  Search this Thread
Old 02-21-2014, 05:40 AM   #1
riva.gupta
LQ Newbie
 
Registered: Jul 2012
Posts: 7

Rep: Reputation: Disabled
Question what does udevtrigger do?


Hi all,

I have some logical disks assigned to my server(RHEL 5.5) from the iSCSI storage for which I have multiple paths. But I am not able to see the correct subpath count as in the file /dev/disk/by-path/ip-192.168.x.x-iscsi-iqn-xxxx

However, when I add the udevtrigger command in /etc/rc.local, I am able to see the correct paths. Can someone please let me know, what udevtrigger exactly does to correct the paths count in /dev/disk/by-path/

Thanks for your help in advance
 
Old 02-22-2014, 05:57 AM   #2
robertjinx
Member
 
Registered: Oct 2007
Location: Prague, CZ
Distribution: RedHat / CentOS / Ubuntu / SUSE / Debian
Posts: 749

Rep: Reputation: 73
udevtrigger: Request device events from the kernel. Primarily used to replay events at system coldplug time.

In other words triggers setup of devices based on kernel events, meaning it adds/removes/changes devices nodes (rights, ownership, acl) and links in /dev, based on some pre-existing rules, usually found in /lib/udev/rules.d and /etc/udev/rules.d
 
Old 02-23-2014, 11:27 PM   #3
riva.gupta
LQ Newbie
 
Registered: Jul 2012
Posts: 7

Original Poster
Rep: Reputation: Disabled
Quote:
Originally Posted by robertjinx View Post
udevtrigger: Request device events from the kernel. Primarily used to replay events at system coldplug time.

In other words triggers setup of devices based on kernel events, meaning it adds/removes/changes devices nodes (rights, ownership, acl) and links in /dev, based on some pre-existing rules, usually found in /lib/udev/rules.d and /etc/udev/rules.d
Does this mean the devices get refreshed when I type the udevtrigger command. Before running udevtrigger, I get wrong number of devices and after running this command, the number of devices is corrected. Is this some sort of bug on RHEL with iSCSI connections?
 
Old 02-24-2014, 09:20 AM   #4
TB0ne
LQ Guru
 
Registered: Jul 2003
Location: Birmingham, Alabama
Distribution: SuSE, RedHat, Slack,CentOS
Posts: 23,646

Rep: Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906
Quote:
Originally Posted by riva.gupta View Post
Does this mean the devices get refreshed when I type the udevtrigger command. Before running udevtrigger, I get wrong number of devices and after running this command, the number of devices is corrected. Is this some sort of bug on RHEL with iSCSI connections?
Again, the best people to ask about bugs with Red Hat would be Red Hat Support...which you don't have, since you're using 5.5. The last supported version of RHEL 5 is 5.9, and that's only under the extended-support option. There have been NUMEROUS bugs fixed between 5.5 and 6.5, which is why people pay for support/updates of RHEL, or they don't use it.

ISCSI devices aren't handled the same way as other devices are.
 
Old 02-25-2014, 12:42 AM   #5
riva.gupta
LQ Newbie
 
Registered: Jul 2012
Posts: 7

Original Poster
Rep: Reputation: Disabled
Quote:
Originally Posted by TB0ne View Post
Again, the best people to ask about bugs with Red Hat would be Red Hat Support...which you don't have, since you're using 5.5. The last supported version of RHEL 5 is 5.9, and that's only under the extended-support option. There have been NUMEROUS bugs fixed between 5.5 and 6.5, which is why people pay for support/updates of RHEL, or they don't use it.

ISCSI devices aren't handled the same way as other devices are.
Hi TBone,
Thanks for ur help. I do not have RHEL support.
My question is why do I need to run udevtrigger when I have not made any changes in /etc/lib/rules.d/****.rules to make the entries correct in /dev/disk/by-path/...
 
Old 02-25-2014, 02:56 AM   #6
robertjinx
Member
 
Registered: Oct 2007
Location: Prague, CZ
Distribution: RedHat / CentOS / Ubuntu / SUSE / Debian
Posts: 749

Rep: Reputation: 73
Then most probably there is a bug which presents itself as not getting ADD/CHANGE kernel events or somehow a broken rule or broken udev. Usually when you run udevtrigger manually is (or should be) based on CHANGE kernel events (by default). This is not 100% sure, as you do have a old version of RH and of course udev.

Trigger can be use for all types of actions, but usually if the ACTION is not mentioned, there is a default, which should be CHANGE, but I'm not 100% sure on this.
 
Old 02-25-2014, 03:07 AM   #7
robertjinx
Member
 
Registered: Oct 2007
Location: Prague, CZ
Distribution: RedHat / CentOS / Ubuntu / SUSE / Debian
Posts: 749

Rep: Reputation: 73
OK, udevtrigger version 095 doesn't seem to have the option of change the ACTION, which might mean it will work on any ACTION (change/add).

Basically it means that something doesn't work right (it might be kernel, or iscsi kernel module, or udev)

What you could do is use 'udevtrigger and the udevsettle':

Code:
udevtrigger
udevsettle --timeout=60 (this is not necessary, but it's better then 180 second, which is default)
For more info use man:

man udevtrigger
man udevsettle
 
1 members found this post helpful.
Old 02-25-2014, 08:50 AM   #8
TB0ne
LQ Guru
 
Registered: Jul 2003
Location: Birmingham, Alabama
Distribution: SuSE, RedHat, Slack,CentOS
Posts: 23,646

Rep: Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906Reputation: 6906
Quote:
Originally Posted by riva.gupta View Post
Hi TBone,
Thanks for ur help. I do not have RHEL support.
Spell out your words, please. And go back and re-read my last post. RHEL 5.5 is not even AVAILABLE for support...you are MANY versions behind, and any bugs in software like this (and there have been SEVERAL reported), have been fixed. If you don't pay for RHEL, then YOU SHOULD NOT BE USING IT in a production environment. You PAY FOR support/updates/bugfixes...if you don't get them, all you're doing is setting yourself up for dealing with problems like this, that have probably ALREADY BEEN FIXED.
Quote:
My question is why do I need to run udevtrigger when I have not made any changes in /etc/lib/rules.d/****.rules to make the entries correct in /dev/disk/by-path/...
And your question was answered. ISCSI devices aren't typical 'devices', and rescanning manually is often the quickest way to pick them up, just like with a SAN device. The LUN may be presented, but not be VISIBLE until the SAN driver is reloaded/refreshed. And AGAIN, this may also be a bug that has been fixed, and available to you if you PAY FOR RHEL.
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
isa pcic probe & udevtrigger retry fail matteovinci Slackware 4 08-07-2009 04:57 AM
Slack boot stops at /sbin/udevtrigger --retry-failed saivin Slackware 3 06-15-2009 01:33 AM
udev, snd_hda_intel and udevtrigger TimoSchmid Debian 2 08-05-2008 09:47 AM
boot hangs at udevtrigger retry-failed after attempt to set up wireless Greenfuse Slackware 3 06-23-2008 07:51 AM
udevtrigger --retry-failed takes ages on boot Chaves Slackware 0 05-28-2008 08:26 AM

LinuxQuestions.org > Forums > Linux Forums > Linux - Server

All times are GMT -5. The time now is 07:07 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration