Difference between revisions of "Hardware servers"
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Er zijn verschillende
Er zijn verschillende WWW-servers .
There are several
There are several WWW-servers .
Revision as of 18:41, 10 January 2013
Servers and Workstations
C&CZ manages ca. 470 Linux workstations, ca. 800 servers and workstations with MS-Windows and ca. 20 Sun/Solaris/SPARC servers, primarily in the domain science.ru.nl. Dual-boot Windows/Linux machines are counted twice.
C&CZ manages (for departments) workstations with Ubuntu Linux or MS-Windows. There are also workstations in the PC-rooms and Study area for general use by anybody with a Science login, but also by all RU employees and students and guests with a temporary login. Almost all those machines are dual-boot, the user can choose to boot Ubuntu Linux or MS-Windows.
- lilo and stitch, the Linux login-server for employees and students.
Ways to log into the login servers:
- With SSH (Secure Shell), which is an encrypted connection, so passwords can't be sniffed. An SSH connection is possible from all over the Internet. It is possible to tunnel X11-traffic (from Xwin32).
- With telnet or rsh. Because passwords can in that case be sniffed from the network, this is only allowed from within the RU/UMCN-campus.
The CPU-load of important servers is being monitored.
Beginning 2006, a number of departments bought a bunch of Sun Fire X4100 dual-processor dual-core machines in order to have more Linux computing power. In 2007 Cluster software was installed. Departments have regularly bought new machines that were added to the cluster. As of October 2011, the cluster totalled 512 cores and 1024 CUDA cores. The CPU-load of the clusternodes is being monitored.
On the Do-It-Yourself website each user can see which mail server will store incoming mail for his account. Mail can be accessed with POP3 and IMAP over SSL. In every domain managed by C&CZ the alias smtp.science.ru.nl points to the machine that accepts mail with the SMTP-protocol. N.B.: If one uses a (non-RU) Internet provider, our mail server will only accept mail for our (RU) mail-addresses. Most other mail will not be accepted ("Relaying Denied!"). One can prevent this by using the smtp-server of the Internet-provider or by using Authenticated SMTP.
The amount of mail and spam is being logged.
There are several WWW-servers with websites and web applications.
The alias printer-srv.science.ru.nl points to the machine that manages almost all queues for the network printers.
These servers share different types of files, e.g. home-directories, application-software and disks for departments and groups. All modern servers only have redundant disks, sometimes by using "mirroring", sometimes by use of a "RAID-array". That means that loss of only 1 disk will nor cause any problem for users.
The disk servers for e.g. home-directories for employees and students have a support contract. Therefore a problem should not continue for many hours.
Faculty departments can rent disk space, at this moment in chunks of 90GB for 90 euro/year, or 200GB for 200 euro/year. Although this is much more expensive than buying 1 disk for 1 PC, it makes sense often, because of the reliability (redundant disks, backup, support contract) and security (stable server). One or more directories can be shared to Windows-PC's by attaching a network share. Unix/Linux computers can mount the same disk through NFS. Reading and/or writing to such a directory is generally only possible for a specific group of logins.
Almost all disks that are managed by C&CZ, are being backupped regularly, in order to be able to restore data in case of small or large calamities.