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====== GNU/Linux Workstations ======
The standard Lorentz Institute workstation runs the GNU/Linux operating system [[https://getfedora.org/en/workstation/|(Fedora 27)]], 64-bit. The workstations 
are configured to host a variety of scientific and non-scientific software to maximize your productivity.
You are allowed to install and/or build packages locally (directories to which you have access), but for system-wide installations you must file a request through our [[https://helpdesk.lorentz.leidenuniv.nl/|helpdesk]] application or via email at ''support@lorentz.leidenuniv.nl''.

Although the workstations might differ in their hardware specifications, they are set so that you can switch from one to the other flawlessly. For instance, the home directories are not local to a particular  machine, but they are `mounted'  as a network file system on each workstation. One of the immediate advantages of this configuration is that 
you can access you home files upon login no matter the workstation you are working on. On the other hand, having the home directories mounted over the network can result in problems if the home file system is 
not accessible, such as in the event of a network disruption.

===== The home disk =====
The home disk is `automounted' on boot. 
<code>
$ df /home
Filesystem         1K-blocks       Used  Available Use% Mounted on
home:/export/home 3170555392 1260111360 1910444032  40% /home
</code>
Each user has an **__allocated quota__** on the home disk depending on their role within the Lorentz Institute. The standard quota is 4GB, nonetheless it is possible to request extra space. To check your quota settings type
<code>
$ quota -s
Disk quotas for user xxxxxx (uid 999x99): 
     Filesystem   space   quota   limit   grace   files   quota   limit   grace
home:/export/home
                 12344K   4786M   4883M             279       0       0        
</code>
:!: TIP: Regularly check that you are below your assigned quota. Your workstation will stop working correctly if softwares cannot write temporary files in your home folder any more.

To compile a list of the ten largest files in a directory execute
<code>
du -h /home/your_username/some_directory | sort -rh | head
</code>
Then clean up responsibly.

==== Home disk data availability ====

The IL home directories are hosted on a iSCSI array of disks arranged in a RAID
configuration. Automatic snapshots (a sort of incremental backup) of the whole home disk are performed __everyday at midnight__. The total number of snapshots stored on our system at any time is __16 snapshots__. In
other words, we should be able to revert to a version of your files that is 16 days old.
===== Local disks =====
Each workstation could have  one or more local hard disks among which one is  used to host the operating system files. 
The remaining space can be used to store relatively large files and will be accessible through the
mount points /data1, /data2,...,/data[n].
<code>
$ df /data[0-9]*
Filesystem      1K-blocks     Used  Available Use% Mounted on
/dev/sda7      1838137644 67915552 1676827048   4% /data1
/dev/md0       1922599800 27092644 1797821652   2% /data2
</code>
Usually /data2 is configured as the mount point of a RAID[1|5] stack, meaning that data in it have a certain level of redundancy which can protect against disk failures. Note however, that storing all of your data on /data2 will not prevent loss if all disks in the array configuration `die' and/or  your computer tower gets destroyed by a fire  or any other disastrous event.

To check if a RAID configuration is used on your workstation type
<code>
$ cat /proc/mdstat 
Personalities : 
unused devices: <none>
</code>
In the example above there are no disks arranged in a RAID.

:!: The backup of any of the data you might have on the ''/data[1,n]'' falls under your responsibility.
===== The shell interpreter =====
The Lorentz workstations come with a set of pre-installed shell interpreters. Your login shell can be chosen upon registration of your Lorentz account (HL 409b). Alternatively, it is possible to use a different
shell interpreter at any time by  just invoking  it, e.g.
<code>
csh 
</code>
===== Access to other workstation disks =====
Partitions named data//1//,...,data//n// are usually network-shared among all the Lorentz Institute workstations. You can access /data1 on a machine called //bingo//  via /net/bingo/data1. More generally, the pattern to access a data disk on a Lorentz machine is
<code>
/net/<workstation>/data<n>
</code>  
Note that in the example above <workstation> can either be //bingo// or //bingo.lorentz.leidenuniv.nl// with no difference. 
TIP: The `mounting' of these network file systems is managed by autofs. This means that those disks will not be mounted until there is an attempt to access them, for instance by contents listing (ls) or change of working directory (cd). 
===== Compilers and libraries =====
A variety of compilers and libraries are available on your workstation. Please refer to the following manual [[linux:sfinx|pages]] for more info.

Here we only give a summary of useful commands.
<code>
# shows which environment modules are available
module avail
# load module 
module load <modulename>
# unload module
module unload <modulename>
</code> 

NOTE: If [[linux:sfinx|sfinx]]  was not installed under your account, you might see less modules on your workstation. In this case make a backup of your settings (for instance .bashrc, .cshrc, etc...) and install [[linux:sfinx|sfinx]]. 
===== Help =====
Should you need assistance operating your workstation, please do not hesitate to request help via our [[https://helpdesk.lorentz.leidenuniv.nl/|helpdesk]] application. You can also visit our offices in the Huygens Laboratory Room 409b at any time during working hours.
 
Comments and suggestions to improve this guide are welcome.
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