The main Linux machine running the cluster is a HP Netserver LC3 server called jove. It has a 400Mhz Pentium II processor, 128 megabytes of RAM and 32 gigabyte RAID. It's located in the basement of Watson Hall in the machine room.
The job of this server, jove, is to run the other Linux machines and services in Engineering IT. Here is a brief list of the main functions of the server: file server, mail server, mailing lists, web server, NIS master, samba and backups.
File serving is accomplished by Network File Services (NFS). NFS basically works by having the server export filesystems to clients. The clients can then mount any or all of the filesystems. The exporting of filesystems by the server is controlled by the /etc/exports file. The mounting of filesystems on the client is controlled by the /etc/fstab file. If you make changes to /etc/exports, you should issue the exportfs -a command to have your changes take effect. Here is what the current /etc/exports file looks like on the server:
/usr/local eitx*.eng.yale.edu(rw,no_root_squash) 130.132.94.123(rw,no_root_squash) /home eitx*.eng.yale.edu(rw,no_root_squash) europa.eng.yale.edu(rw,no_root_squ ash)
The rw option lets users both read and write (if they have permission) to the disks from the client machines. The no_root_squash option allows root to have write permission from the client machines.
/home is where home directories are located. The default home directory for users, or disk location, is /home/USERNAME, where USERNAME is YOUR username (your NetID).
/usr/local is where third party and other additional software is kept.
Here is a sample /etc/fstab from a client machine. I will ONLY list the NFS directories since the local directories may vary from machine to machine:
jove:/usr/local /usr/local nfs bg,hard,intr,rsize=8196,wsize=8196,exec,dev,suid,rw jove:/home /home nfs bg,hard,intr,rsize=8196,wsize=8196,exec,dev,suid,rw
The option bg mounts to filesystem in background.
The option hard means it's a hard mount.
The option intr means you can interrupt the NFS mount if it hangs.
The options rsize=8196 and wsize=8196 set the read and write buffers to 8196 bytes which helps increase performance.
The option exec permits execution of binaries.
The option dev interprets character or block special devices on the file system.
The option suid allows set-user-identifier or set-group-identifier bits to take effect.
The option rw means the filesystem is mounted with read and write permission.
The first column shows the server name and filesystem exported by /etc/exports on the server. The second column shows where that filesystem is mounted on the local client machine.
The start, stop, status and reload script for NFS is /etc/rc.d/init.d/nfs
The official policy in the department is that we are not running a mail server. All people must receive email at the Pantheon or some other outside mail server. The fact is we are running a mail server. The primary functions of the mail server are: redirect any incoming mail to real mailboxes (most likely this is the Pantheon), bounce mail for people that have failed to provide a valid external mailbox but do have a valid account, rewrite outgoing mail return addresses and run the mailing lists.
The mail server we are running is called postfix. We are not running sendmail. Postfix attempts to be fast, easy to administer, and secure, while at the same time being sendmail compatible enough to not upset existing users. To learn more about postfix and join the mailing list you should visit here: http://www.postfix.org/
The postfix configuration and database files are located in /etc/postfix on the server. The main configuration file is called main.cf. There are several sample configuration files if you wish to add functionality. The two database files also being used are canonical and relocated. canonical is the redirect and rewriting list. It's a two column ASCII file with the local username in the first column and the address to redirect and rewrite mail to in the second column (most likely first.last@yale.edu). relocated is the bounce list. It's a two column ASCII file with the local username in the first column and the Pantheon phone directory in the second column.
If you make a change to either canonical or relocated the changes will take effect automatically in a few hours. In most cases, it's probably needed to make the changes take effect immediately. To do this, you simply remake the database by typing /usr/sbin/postmap "database-file" where "database-file" is either canonical or relocated. Next you must reload the new database into postfix. To do this simply type /etc/rc.d/init.d/postfix reload.
The start, stop, status and reload script for postfix is /etc/rc.d/init.d/postfix
Email lists are maintained by a program called mailman. mailman has both a web interface and command line scripts available. Mailman is software to help manage email discussion lists, much like Majordomo and Smartmail. Unlike most similar products, Mailman gives each mailing list a web page, and allows users to subscribe, unsubscribe, etc. over the web. Even the list manager can administer his or her list entirely from the web. Mailman also integrates most things people want to do with mailing lists, including archiving, mail-to-news gateways, and so on. Mailman has all of the features you expect from such a product, plus integrated support for the web (including web based archiving), automated bounce handling and integrated spam prevention. To find out more about mailman and join the mailing list just visit: http://www.list.org/ Here is a brief overview of features:
The mailman configuration web pages are located at http://jove.eng.yale.edu/mailman/admin/. Some lists may not appear on the web page because we don't want everyone to know about all the lists. To view a specific mailing list just append the name of the list to the URL, faculty for example. Please see Martin Ewing for the administrative password of the lists. Here is a list of possible mailing lists:
List Description Ap-faculty-adjem AP faculty, adjunct & emeritus Ap-faculty-jfoe AP faculty, joint in FoE Ap-faculty-jxfoe AP faculty, joint outside FoE Ap-faculty-primary AP faculty, primary appointments Ap-faculty-research AP Research Faculty Bulletin Yale Engineering Bulletin Bulletin-ext Yale Engineering Bulletin (external ed) Ce-faculty Yale Chemical Engineering Faculty EAS-INFO EAS Internet Information List (pjk) Ee-faculty Yale Electrical Engineering Faculty Eit-staff Faculty of Engineering IT Office Staff Eng-admin-staff Faculty of Engineering Staff Eng-sysadmins Engineering sysadmins (tier 1 support) Me-faculty Yale Mechanical Engineering Faculty Ysm Yale Scientific Magazine - Editors Ysm-staff Yale Scientific Magazine - Staff
To use the command line interface, simply su mailman. The scripts are in the bin directory. Use these scripts to quickly create a new list or list the members of a list.
Here are the brief directions for creating a new list:
sudo su - mailman
cd bin
newlist <list-name> <list-admin's-address> <admin-password>
Five or six alias line will be echoed out. Copy them and paste them
in /home/mailman/mail/aliases. You'll see all the other mailman lists
there so you can follow the syntax if you get lost.
Exit the user Mailman
sudo /usr/sbin/postalias /home/mailman/mail/aliases
sudo /etc/rc.d/init.d/postfix reload
You can reset the password by visiting the list's admin page and using the site password. You can then scroll down and reset the admin password for that list. Now if you forgot the site password, you'll have to "sudo su - mailman" and run " mailman/bin/mmsitepass" to reset the site password first.
We are running the apache web server. To learn more about the apache web server just visit http://www.apache.org/ The home page is http://jove.eng.yale.edu/, which is just the apache "It Worked!" page. The home page documents are located under /home/httpd/html. Individual home pages can be created under the public_html subdirectory under a user's home directory. The home page file name is index.html.
The configuration files are located in /etc/httpd/conf. There are far too many options to list here. The main restriction is to the documentation pages. They are restricted to the Yale domain. The Big Brother pages are world readable. Currently the only pages are documentation, Big Brother and Mailman.
The log files are in /var/log/httpd. The logs are rotated and compressed once a week. They rotation happens are 5am Sunday morning. The rotation schedule and compressing is controlled by /etc/logrotate.conf and /etc/logrotate.d/apache.
There is a file /home/httpd/html/robots.txt. This file is used to stop robots, spiders and search engines from indexing certain web pages. Right now the documentation and Big Brother pages are listed. You may wish to add other areas of the web server.
The start, stop, status and reload script for the web server is /etc/rc.d/init.d/httpd
The departmental server is running Network Information Services (NIS). The server is the NIS master. So it contains all the source and database files that get shared throughout the cluster. NIS can share many pieces of information both standard and custom information. These bits of information are called NIS maps. Currently the server is sharing the following maps: group, hosts, netgroup, passwd and shadow. All of the source files for these maps are located in /etc. If you make a change to one of the source files you must propagate the NIS map out to the clients. To do this:
cd /var/yp make
The NIS domain name is eng-it. The NIS maps are created and stored in /var/yp/eng-it. Just run the Makefile in /var/yp to recreate and push out the NIS maps. The file /var/yp/ypservers contains a list of the NIS servers. Currently just the department server is serving NIS maps, there are no NIS slave servers.
Access to the NIS maps is restricted to the department. This is controlled by the /etc/hosts.allow and /etc/hosts.deny files since TCP wrappers are used by NIS.
There is an NIS password daemon running which allows users to change their NIS passwords. The daemon is called yppasswdd. To start, stop, status and reload the NIS password server /etc/rc.d/init.d/yppasswdd. It is monitored by Big Brother, so you will know when it dies. Simply restart it.
I added an entry in the root crontab to push out the NIS maps every ten minutes. Use "crontab -l" as root to view the root crontab. There should be an entry as follows:
# Make sure NIS maps stay current 29Aug2000 PAG */10 * * * * cd /var/yp; make >/dev/null 2>&1
The start, stop, status and reload script for the NIS server is /etc/rc.d/init.d/ypserv
The Samba software suite is a collection of programs that implements the Server Message Block(commonly abbreviated as SMB) protocol for UNIX systems. This protocol is sometimes also referred to as the Common Internet File System (CIFS), LanManager or NetBIOS protocol. Basically Samba is used to talk "Windows". To learn more about Samba, read the man pages (man samba) or visit http://www.samba.org/
Samba is used in the cluster so users of Windows machines can have direct access to their home directories on the cluster server. On the Windows side of things, this is called "mapping a network drive".
The samba configuration file is /etc/smb.conf. The samba server is configured to use the YALE NT domain to verify credentials. This eliminates the need for samba usernames and passwords. The only constraint is that the samba user's local Linux account name and NetID MUST be the same.
When a Windows user is using samba for the first time, his/her YALE NT password may not be synchronized with their UNIX (Pantheon) password. This is particularly true for someone that has never logged into the YALE NT domain before. They will have to synchronize their UNIX and NT passwords on the Pantheon first. To accomplish this, the user should visit: http://www.yale.edu/password/
The start, stop, status and reload script for Samba is /etc/rc.d/init.d/smb
The ADSM backup service performs an incremental backup of all newly created files each day. The files are copied to the tape robot system at 155 Whitney Ave. For the most part, the system is hands off. The process runs every night. The ADSM directory is /usr/adsm. The log files get rotated and compressed once a week. The scripts to control this are /etc/logrotate.d/adsm and /etc/logrotate.conf The start, stop script is in /etc/rc.d/init.d/adsm. You can read more about ADSM at http://wss.yale.edu/doco/ADSM/
The ADSM client occasionally hangs. There are two scripts that check the size and date of the ADSM log file once a day. If log file is less than 1K or older that 1.5 days an email is send to out. These scripts can be found in /etc/cron.daily with obvious file names. You can read more about ADSM at http://wss.yale.edu/doco/ADSM/
If you ever have to recover file(s) using ADSM, simply start the client /usr/adsm/dsm and select the files you wish to restore. Most likely the files you want to recover have been deleted more than a day ago. They will not show up on the active list. You'll need to change your view to display inactive files or set a date to one when you know the files did exist on the disk. To display the inactive files, click on "Restore Files and Directories to your system". Then click on "View" and "Display inactive files". This should give you a complete list of all current files and ones that you have deleted locally.