Suse Tips

[Aug 7, 2009] atd daemon is not running on Suse 10 SP2 by default, so command at fails

It needs to be manually enabled, if we need consistency with the Solaris behavior.

Configuring Apache using YaST, openSUSE 10.2

YaST " Bozzie Software

Filed under: Apache, SUSE, Subversion, SysAdmin, YaST, opensuse - Bozzie @ 3:36 am

I configure Apache2 on openSUSE with YaST rather than editing the configuration files directly. If this is your first time installing Apache on openSUSE, I highly recommend it. YaST is a big time-saver for two aspects of Apache configuration: the initial installation and adding, enabling, and disabling server modules. A default server configuration supporting Perl and PHP can be up and running in less than an hour using YaST.

YaST isn't good at all facets of Apache configuration so some editing of conf files may eventually be needed. If manual editing is required, why not use it exclusively? Because once you go manual, you can't switch back to YaST when major changes are needed. I like the fact that if I install a new web application that needs several additional Apache modules, I can use YaST to enable them in a couple of minutes, often without having to learn anything about them.

I also like the fact that using YaST to configure Apache will give me a configuration closely matched to thousands of other openSUSE Apache servers. This makes it likely that I will get a functional, robust httpd set up at the start. Then I can incrementally add modules and customizations as needed, testing as I go.

Following is a YaST-based recipe to install a straightforward httpd configuration with Perl, PHP, and mod_userdir enabled. Subversion, WebDAV, and virtual host support are also added (using some conf file editing). Finally, the added bookkeeping steps that allow YaST and hand-edited conf files to co-exist are presented.

Part I: Content-Independent Configuration

Part 1 installs a functional (but empty) httpd server with all modules and parameters properly configured. Connections to the site-specific content are discussed in Part 2.

1. OpenSUSE scatters Apache conf files among /etc/apache2 and its conf.d, sysconfig.d and vhosts.d sub-directories. Keep a copy of the original conf files to determine what YaST has done and add source code control repositories to manage manually edited files:
   • cd /etc/apache2
   • mkdir ORIG; cp -p *.conf ORIG
   • mkdir RCS
   • Repeat for the three ".d" subdirectories.
2. Start YaST/ Network Services/ HTTP Server:
   • Turn on php, perl, python and/or ruby in a special configuration page that only appears once (one can still turn these on/off later, but it's easier to do here).
   • Accept defaults in the Server Wizard (5 pages), except choose Start When Booting on page 5.
   • Click Advanced Configuration.
   • In the Server Modules tab, enable dav, dav_fs, info, rewrite and status.
   • Needed to Add Module for dav_svn but the YaST screen would not accept input, so I hit Finish (will add in Step 3).
     
   • The server starts. http://localhost just says "It works!" instead of the normal Apache welcome page. Didn't like this so I copied index.html from an old SUSE 10.0 installation.
   • Read the comments in all of the /etc/apache2/conf.d/*.conf files, some of which are controlled by IfDefine blocks. For my installation, I learned I needed to add the SVN_DOC and SVN_VIEWCVS flags (next step).
3. Start YaST/ System/ sysconfig Editor:
   • Select Network, WWW, Apache2.
   • Highlight APACHE_MODULES. Add dav_svn into the Modules line. Note: Don't hand-edit dav_svn into /etc/apache2/sysconfig.d/loadmodule.conf, as YaST will just remove it next time it runs.
   • Highlight APACHE_SERVER_FLAGS. Type "SVN_DOC SVN_VIEWCVS" into the text field.
   • Finish.
4. A diff of ORIG/default-server.conf with the one YaST created shows that YaST removed the mod_userdir section, changed indents, and added ServerName and ServerAdmin. Thus I chose the original distribution .conf as my starting point:
   • mv default-server.conf{,.YAST}
   • cp ORIG/default-server.conf .

   • ci -l default-server.conf
   • Edit with a text editor and copy the ServerName and ServerAdmin directives from the YaST version into default-server.conf.
   • ci -l default-server.conf
5. Restart YaST/ Network Services/ HTTP Server:
   • Select the Server Modules tab and verify that the dav_svn module appears.
   • Exit or Abort.
   • Note: from this point forward, if YaST/HTTP Server is re-run and Finish is clicked, default-server.conf and /etc/sysconfig/apache2 will be overwritten. Capture a snapshot before running or retrieve original from RCS archive afterward.
6. Check the syntax of all configuration files and reload httpd:
   rcapache2 restart-hup
7. Browse http://localhost/server-info and server-status. Verify all desired modules are present and running.
8. Browse //localhost/manual and localhost/svn-manual to see documentation.

The content-independent phase of installation is complete.

Part II: Serving Local Site Content

To prepare for Part 2, load all content files that are outside of the server document root (e.g. Subversion repositories, WebDAV directories, and user public_html areas). I keep my Subversion repositories under /home/wwwrun/svn, giving them the same owner and group as the httpd process.

1. Verify that browsing a http://localhost/~<username> directory works.
2. Subversion repository configuration goes in the /etc/apache2/conf.d/subversion.conf file. I piggybacked the WebDAV configuration into this file rather than creating a separate file: subversion.conf. Also, I add Basic Auth to ViewVC in subversion.viewvc.conf (see earlier blog entry for an explanation).
3. Use htpasswd2 to create the basic authentication password file.
4. Create a /var/lock/apache2 directory (user wwwrun, group www).
5. rcapache2 configtest
6. rcapache2 restart-hup
7. Browse http://localhost/svn/<reponame>. Username and password are requested and the repository appears. Run RapidSVN from a Windows machine to verify connectivity.
8. Edit /srv/viewvc/viewvc.conf to add root or root_parents, default root, and mailto.
9. Browse http://localhost/viewvc , username and password are requested, then the ViewVC page appears. Click on the "ViewVC Help" hyperlink and the documentation appears.
10. Using Konqueror, browse webdav://localhost/fs and a folder view of the WebDAV folder appears.
11. See this blog entry for details of connecting to WebDAV via WindowsXP.

All of my local Subversion, WebDAV, and web page content is now available via Apache.

Part III: Virtual Hosts

Finally I'll add virtual hosts for my various development, prototype, and staging areas. The YaST HTTP Server GUI offers a screen to do this, but I chose to start with the as-delivered file just as with default-server.conf.

1. Create a new conf file in /etc/apache2/vhosts.d (e.g. LLvhost.conf in my case). I copied the vhost.template as the starting point.
2. I defined four virtual servers:
   • localhost - contains only a ServerName statement to serve as the default server.
   • llxxx - three name-based servers that have document roots in various code development sub-directories. Each of these gets a separate set of error and access log files.
3. Uncomment the NameVirtualHost *:80 line in /etc/apache2/listen.conf.
4. Add the three name-based server names to /etc/hosts as synonyms for localhost.
5. rcapache2 configtest
6. rcapache2 restart-hup
7. Browse http://llxxx and the virtual host content appears. Verify that log information appears in the correct file pair in /var/log/apache2.

Part IV: Configuration Control and Maintenance

The Apache server installation is now complete. But adding source code control is necessary to safely re-run YaST/ Network Services/ HTTP Server Configuration in the future. Whenever HTTP Server Configuration is ended with Save or Finish, any of the conf files may be overwritten, obliterating prior manual edits. Source code control allows us to manage and resolve this conflict.

Using the unaltered conf files in the ORIG directories as references, perform a diff of all of the conf files to learn which have been customized. Any altered conf files that were hand-edited should be placed under configuration control (e.g. CVS, Subversion, RCS). Consider controlling the YaST-altered files as well.

I maintain five files in RCS: default-server.conf, mod_userdir.conf, subversion.conf, subversion.viewvc.conf, LLvhost.conf. After saving any new HTTP Server Configuration session, I use rcsdiff to learn what changes have been made to these files. Review the changes and either restore the last version from RCS or check in a new revision as appropriate.

How To Disable ZENworks ZMD, openSUSE 10.2

Filed under: SUSE, SysAdmin, opensuse - Bozzie @ 5:41 pm

The openSUSE 10.2 update repository that I was connected to stopped receiving updates from the mother ship in late November. I checked some other mirrors and found them to be in the same state. Only the main ftp.suse.com repository is current (as of this post). I could find no mention of this problem on openSUSE.org.

This problem plus the announcement of openSUSE 11.0 Alpha caused me to reconsider my upgrade plans. I am happy with 10.2 but was planning to upgrade to 10.3 solely to eliminate the nightly 1.5 hour zmd update runs (which I've complained about at length in a previous post).

Since I am now going to have to poke around with updating anyway, I decided to look once more for instructions on how to disable the ZENworks ZEN management daemon (zmd). If I succeed in turning off zmd, I may skip the 10.3 release entirely and go directly from 10.2 to 11.0.

I found this openSUSE-Community.org article which provides simple instructions for disabling and removing zmd. Using it as a guide, I performed the following steps:

1. rczmd stop - this stopped zmd. Hallelujah! I've never known how to do this before now.
2. Start the YaST, Software, Installation Source GUI.
3. Add ftp.suse.com/pub/suse/update/10.2 as a new catalog.
4. Disable (status = Off, update = Off) the old (utah.edu) mirror catalog. This catalog can be removed once the ftp catalog is working.
5. Uncheck the "Synchronize with ZENworks" check box.
6. Click Finish.
7. The catalog information was successfully downloaded from ftp.suse.com, new updates appeared in the updater applet, and were successfully applied. Everything seems to be working.
8. I restarted the Installation Source GUI and was dismayed to see the "Synchronize with ZENworks" box still checked. Don't know if it is still turned on, or if the GUI is just urging me to turn it back on.
9. Leaving zmd turned off but still installed, I let the system run for a few days until I verified that newly released updates from openSUSE were reported in the updater applet.
10. Once verified, I removed the zmd related packages as described in the article:
    rpm -e zmd libzypp-zmd-backend sqlite-zmd rug zen-updater
11. Restarted the Installation Source GUI: the "Synchronize with ZENworks" box is now grayed out.
12. Rebooted; start-up works fine without ZENworks zmd.

Updater Applet:

If you are running KDE, you may need to perform the following step:

1. Switch the panel updater applet (controlled by /etc/sysconfig/sw_management) from zlm (the zen-updater update manager) to opensuse.

I had already done this manually during my previous battles with zmd, but I have some recollection that it will happen automatically if the zen-updater application isn't found. For Gnome, I don't know what applet (if any) will appear in the panel.

SMART smartd Configuration, openSUSE 10.2

Filed under: SUSE, SysAdmin, opensuse - Bozzie @ 8:10 pm

Stumbled across smartd in YaST/System/System Services (runlevel) and turned it on. In addition to monitoring the long-term health trend of the disk, SMART also provides interesting real-time information about the hard drive: total hours, number of power cycles, current temperature, etc. I liked smartmontools so much that I also installed it on my WindowsXP machines, along with HDD Health.

I configured /etc/smartd.conf after reading the smartd.conf and smartctl man pages, the smartd log entries in the messages file, and comments within the file itself. Current setup:

  /dev/sda -d sat \
  -a -o off -S on \
  -s (O/../.././07|S/../.[27]/./08|L/.[02468]/15/./08) \
  -m root@localhost -M test

Notes on the configuration parameters:

1. -d sat - lots of testing to determine this should be sat (SCSI to ATA Translation) and not ata. The various man pages are vague, with one saying "follow the hints appearing in the log file." Well, the hint in my log file said "use -d ata or -d sat" (sigh). Both seemed to work, so I began with sat since the libata library is present. Subsequent tests of ata produced command failure messages in the log, thus sat is correct.
2. -a - turn on the default recommended set of monitoring functions.
3. -S on - "S" is variously described as "turning on SMART" or "turning on Attribute Autosave". I believe this is a modal parameter within the disk drive itself, and starting smartd turns this on by default. The manual recommends adding to the configuration to ensure it doesn't get shut off. It echoes "enabled SMART Attribute Autosave" to messages, reassuring me that SMART is running.
4. -o off - "o" controls "SMART Automatic Offline Testing" (data collection really, not testing). The man page says this command is obsolete and that the collection intervals are chosen by the disk manufacturer. The "O" offline test (discussed next) causes the same data to be collected.
5. -s REGEXP - schedule various off-line tests My schedule: O (offline immediate), every day, 7am; S (Short), every 5 days, 8am; L (Long) - 15th of alternate months. I haven't discovered what the differences are between the short and long tests (for my disk the short test takes 2 minutes vs. 98 minutes for the long test).
6. -m, -M - email address for important messages. "-M test" sends an email on startup to confirm everything is working.
7. -i N - (command line only, not conf file) set the interval for polling the disk. Seems like this shoud be controllable from the conf file, but since it isn't I'm staying with the default of 30 minutes.

Notes:

On Linux, "smartctl -c" always showed a failure in the offline data collection status:

(0×05) Offline data collection activity was aborted by an interrupting command from host.
Auto Offline Data Collection: Disabled.

Examining the messages file shows auto-collection being enabled and the scheduled offline collection being started. Everything seems normal, but auto-collection becomes disabled at some point. On two WindowsXP PCs, data collection activity completes normally and Offline Collection is enabled. I don't know how auto-collection was enabled on these two machines; perhaps HDD Health did it.

Is the Linux collection failure connected with auto-collection becoming disabled? First attempt at solution: switched from "-o on" to off after realizing that my scheduled testing ran the same test. Changed short test schedule to one per week in case it was causing the interruption. The problem has gone away and smartctl now reports "data collection activity was completed without error".

References:

• Wikipedia - best description of the SMART attributes that I found (other than the spec itself which is exhausting). The external link "Out SMART your hard drive" helped explain why the raw data was different between my Maxtor and Seagate hard drives.
• smartmontools - home page for the SMART tools. They are installed by default in openSUSE Linux, and available for download for Windows XP.
• HDD Health - a graphical user interface that presents current SMART information and failure alerts for Windows PCs. Still need smartmontools to trigger the offline tests.

[Dec 14, 2008] Cool Solutions Using ClusterSSH to Perform Tasks on Multiple Servers Simultaneously By Martijn Pepping

Problem:

As an administrator of SLES/OES Linux clusters or multiple SUSE Linux servers you are probably familiar with that fact that you have to make an identical change on more than one server. Those can be things like editing files, execute commands, collect data or some other administrative task.

There are a couple of way to do this. You can write a script that performs the change for you, or you can SSH into a server, make the change and repeat that task manually for every server.

Now both ways can cost an extended amount of time. Writing and testing a shell script takes some time and performing the task by hand on lets say five or more servers also costs time.

Now, wouldn't it be a real timesaver when you have only one console in which you can perform tasks on multiple servers simultaneously? This solution can be found in ClusterSSH.

Solution:

With ClusterSSH it is possible to make a SSH connection to multiple servers and perform tasks from one single command window, without any scripting. The 'cssh' command lets you connect to any server specified as a command line argument, or to groups of servers (or cluster nodes) defined in a configuration file.

The 'cssh' command opens a terminal window to every server which can be used to review the output sent from the cssh-console, or to edit a single host directly. Commands given in to the cssh-console are executed on every connected host. When you start typing in the cssh-console you'll see that the same command also show up on the commandline of the connected systems.

The state of connected systems can be toggled from the cssh-console. So if you want to exclude certain hosts temporarily from specific command, you can do this with a single mouseclick. Also, hosts can be added on the fly and open terminal windows can automatically be rearranged.

One caveat to be aware of is when editing files. Never assume that file is identical on all systems. For example, lines in a file you are editing may be in a different order. Don't just go to a certain line in a file and start editing. Instead search for the text you want to exit, just to be sure the correct text is edited on all connected systems.

Example:

Configuration files section from the man-page:

/etc/clusters

This file contains a list of tags to server names mappings. When any name is used on the command line it is checked to see if it is a tag in /etc/clusters (or the .csshrc file, or any additional cluster file specified by -c). If it is a tag, then the tag is replaced with the list of servers from the file. The file is formatted as follows:

<tag> [user@]<server> [user@]<server> [...]

i.e.

# List of servers in live

live admin1@server1 admin2@server2 server3 server4

Clusters may also be specified within the users .csshrc file, as documented below.

/etc/csshrc & $HOME/.csshrc

This file contains configuration overrides - the defaults are as marked. Default options are overwritten first by the global file, and then by the user file.

Environment:

ClusterSSH can be used to any system running the SSH daemon.

• ClusterSSH RPM for openSUSE 10.2/10.3 and SLE10 are available through the openSUSE Build-service: http://download.opensuse.org/repositories/home:/martijn/
• The ClusterSSH sourcecode can be downloaded from: http://sourceforge.net/project/showfiles.php?group_id=89139

[Nov 30, 2007] freshmeat.net Project details for Expect-lite

About:
Expect-lite is a wrapper for expect, created to make expect programming even easier. The wrapper permits the creation of expect script command files by using special character(s) at the beginning of each line to indicate the expect-lite action. Basic expect-lite scripts can be created by simply cutting and pasting text from a terminal window into a script, and adding '>' '

Release focus: Major feature enhancements

Changes:
The entire command script read subsystem has changed. The previous system read directly from the script file. The new system reads the script file into a buffer, which can be randomly accessed. This permits looping (realistically only repeat loops). Infinite loop protection has been added. Variable increment and decrement have been added to support looping.

Author:
Craig Miller [contact developer]

[Nov 30, 2007] Got more than a gig of RAM and 32-bit Linux Here's how to use it By Bruce Byfield

September 21, 2007 | Linux.com

Nowadays, many machines are running with 2-4 gigabytes of RAM, and their owners are discovering a problem: When they run 32-bit GNU/Linux distributions, their extra RAM is not being used. Fortunately, correcting the problem is only a matter of installing or building a kernel with a few specific parameters enabled or disabled.

The problem exists because 32-bit Linux kernels are designed to access only 1GB of RAM by default. The workaround for this limitation is vaguely reminiscent of the virtual memory solution once used by DOS, with a high memory area of virtual memory being constantly mapped to physical addresses. This high memory can be enabled for up to 4GB by one kernel parameter, or up to 64GB on a Pentium Pro or higher processor with another parameter. However, since these parameters have not been needed on most machines until recently, the standard kernels in many distributions have not enabled them.

Increasingly, many distributions are enabling high memory for 4GB. Ubuntu default kernels have been enabling this process at least since version 6.10, and so have Fedora 7's. By contrast, Debian's default 486 kernels do not. Few distros, if any, enable 64GB by default.

To check whether your kernel is configured to use all your RAM, enter the command free -m. This command gives you the total amount of unused RAM on your system, as well as the size of your swap file, in megabytes. If the total memory is 885, then no high memory is enabled on your system (the rest of the first gigabyte is reserved by the kernel for its own purposes). Similarly, if the result shows over 1 gigabyte but less than 4GB when you know you have more, then the 4GB parameter is enabled, but not the 64GB one. In either case, you will need to add a new kernel to take full advantage of your RAM.

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