||<style="background-color: #FF5555"> /!\ ~+ '''PRELIMINARY''' +~  /!\ ||

<<TableOfContents>>

== About Scientific Linux 4 at DESY, Zeuthen ==

SL4 is no longer supported, nor available. The few remaining systems accessible to end users were shut down March 1st, 2012.

== General Points ==

=== AFS Sysname List ===

The AFS sysname list (the output of the `fs sysname` command) in Zeuthen
<<FootNote(Scientific Linux DESY 4, as provided by - IT - in Hamburg, has very different lists, featuring the default sysname as defined by the AFS elders a the very end, a newly invented one at the very beginning, and sysnames that were never in use anywhere in between. We stubbornly refuse to be compatible with this.)>>
is:

||<rowstyle="background-color: #E0E0FF;">Platform     |||||||||||| Sysname List ||
||<style="background-color: #E0E0FF;">32bit (i686)   ||               ||              || i386_linux26 || i586_rhel30 || i586_linux24 || i386_linux24 ||
||<style="background-color: #E0E0FF;">64bit (x86_64) || amd64_linux26 || amd64_rhel30 || i386_linux26 || i586_rhel30 || i586_linux24 || i386_linux24 ||

It is not clear at all that ''amd64_rhel30 i386_linux26'' is the order that makes most sense for the 64bit platform. Opinions on whether or not ''i386_linux26 amd64_rhel30'' would be better are welcome, and this may be changed early on during SL4 lifetime.

=== Login Shells ===

We made a serious effort to make '''bash''' a supported '''login shell''', but it's '''impossible'''.

There is no way to reliably give bash users a working environment identical to that of zsh and tcsh
users, due to bash's limited functionality w.r.t. startup files processing.

We recommend using zsh, zsh or zsh as the login shell. Tcsh is available for those who insist.
Bash is not, sorry.

Notice this does not prevent users from writing or using bash scripts in any way.

=== Language Support, UTF8 ===

It was initially planned to introduce use of UTF8 as the default with SL4. Alas,
it was found that it's causing too much trouble, and makes things too incompatible
to the rest of our environment.

Hence the default for the `LANG` environment variable on SL4 systems is `C`, as on
SL3 and DL5 before. Early SL4 systems had a default of `en_US`, because it makes certain GNOME
applications behave more sensible (in particular gnome-terminal), but it was found to cause
other problems (among them, changes in the date format and sorting order). 

Any user may change the personal default by creating a file `~/.i18n`:
{{{
# recommended and default:
#LANG=C

# alternative:
#LANG=en_US

# I want to suffer
LANG=en_US.UTF-8
}}}

We do ''not'' install language support packages for other languages than US-english,
with the sole exception of dictionaries for spellchecking. Languages other than english
for the user interface are not supported.

=== Removable Media and Hotplug Storage Devices ===

 * '''Mount points''' are now in `/media`. They are created, together with an according
 fstab entry allowing the user logged in on the console to mount it, when the devie is
 plugged in. They are removed, together with the fstab entry, when the device is removed.

  ||<rowstyle="background-color: #E0E0FF;"> Device || Known Mount Points in `/media` ||
  || CD/DVD drives || `cdrom`<<BR>>`cdrecorder` ||
  || USB Storage   || `Mobile_Disk`<<BR>>`usbdisk` ||
  || Floppy Disk   || `floppy` ||

 * '''Firewire''' (aka IEEE1394) does not work. SL does not ship any drivers, nor does
 the upstream Linux distribution, since these drivers have stability issues as well as
 security problems.
 * '''Floppies''' stopped working in all nereide/oceanide class systems (all Pentium 4
 in a white box from Comptronic) with an early DL5 kernel update, and never worked
 there under SL3. On ''some'' of these systems, it works under SL4, on others it still
 does not and there's nothing we can do about it.
 * '''Hotplug''' should work better than on SL3, thanks to the more modern kernel and hotplug
 scripts. It is known to ''not'' work perfectly in all cases though. In particular,
 it was observed that a USB memory stick had to be plugged in twice before it was
 recognized properly.
  * Multiple partitions on USB storage devices should work now, at least if all
  partitions have a supported filesystem, and the partition table format is legal.
  * The new hotplug system does ''not'' assign ownership of the device to the user.
  Hence you can't partition the device or create filesystems, unlike on SL3.
  * The new hotplug system will clean up properly if a mounted device if removed,
  and it no longer causes problems to log out while a hotplug device is mounted.
  ||<style="background-color: #FF7777;"> <!> It is still recommended to''always'' umount all filesystems on a hotplug device before removing it physically, and before logging off from the console. ||
  Notice the GNOME desktop will automount filesystems on hotplug devices when they are
  connected. This feature can be turned off under ''Applications->Preferences->Removable Storage'':
  <<BR>>{{attachment:medpref.png}}

=== Printing ===
  * Print Service has been changed from LPRng to [[Printing_with_Cups| Cups]] because LPRng is obsolete and Cups is better integrated in KDE, Gnome, Open``Office and other tools.

== Backward Compatibility ==

=== Binaries ===
SL4 should be '''binary backward compatible with SL3'''. This means
that executables built on and for SL3 should work on SL4. It does ''not''
mean that any executable that works on SL3 will work on SL4 as well:
If it worked only due to legacy support before, it may no longer work on SL4.
In particular, '''starting with SL4, a.out executables are no longer supported'''.

As on SL3 already, '''no libc5''' is available.

=== Desktop/User Environment ===

 * The '''Display Manager''' was changed from the familiar kdm to '''gdm'''.
  * Because that's the default on SL.
  * And because the binary is built as a ''Position Independent Executable'' - which is a security
  advantage - while the kdm one is not.
  * Gdm will remember your preferred session without the need to
  move some configuration file, but it doesn't know about the rpeference set for kdm, hence '''the
  session type has to be chosen at least once'''.
 * '''HEPi``X11 was dropped'''
  * '''fvwm2 is no longer available'''.
  * Configuration in `~/.hepix` is no longer used.
  * The ''Windows''-Key can no longer be used to type german Umlaute (äöÜ...).
  * Instead, the '''right ''Alt''-Key now works as a ''Compose Character''-Key''': To input an `ä`,
  type `[R-Alt]`, then `"`, then `a` (one after another, not simultaneously). This is slightly
  less convenient, but much more general: This method works for characters like ç ñ ø ô ë ...
 * The old '''HEPi``X profiles were completely replaced'''
  * The replacement is HEPi``X-like where not incompatible with today's defaults on vanilla linux systems.
 * '''KDE, GNOME, Ice``WM, Window``Maker''' are available as on SL3.
  * Ice``WM is the recommended window manager for older desktops with 256 or even 128 MB RAM
  * an enhanced default configuration for Ice``WM is underway

== Software ==

=== Desktop/Office ===

 * Recommended '''browser: firefox'''.

 This is provided as it comes with SL4, with a few configuration changes
 (like locating the cache in /tmp instead of ~).

 If you must use konqueror, please limit the disk cache to a small value or you
 will waste lots of space in ~ and lots of backup for it. The disk location of
 konqueror can't be changed.

 * Recommended '''mail reader: pine'''.

 Provided as coming with SL, plus local configuration changes.

 Reasons:
  * Very low memory requirements, and nice to the mail server, but full feature set.
  * The only reader that can be used remotely over a low bandwidth link.
  * No known case of missed or lost mails due to a pine malfunction. This is quite different
  for many other mail readers.

 Alternatives, all provided ''as is'':
  * thunderbird
  * kmail
  * evolution

 * '''Office Suite: Open``Office.org'''

 We provide a recent version from the openoffice.org site instead of the older one coming
 with SL, plus several dictionaries, plus a few configuration changes.

 * '''PDF Viewer: Adobe Reader'''

 In addition, we provide the Asian Font Pack. Needed for example for documents
 with a japanese abstract.

 Alternative: '''xpdf'''

 * '''Mind Maps: freemind'''

 Updated w.r.t. SL3.

 * Recommended '''Calendar: ???'''

 Unfortunately, '''plan is dead'''. It is no longer maintained. If we provide it
 anyway, that's mostly because it's not yet clear what the recommended replacement
 should be:
  * KDE users may want to try '''korganizer'''. Alas, it doesn't work well without a full KDE session.
  * '''evolution''' has a nice calendar.
  * We provide '''sunbird''', a calendar application from mozilla.org. Although it's still young
  (release 0.3 at the time of writing this), it seems quite usable. What makes it attractive
  is its availability on other platforms (Windows, Solaris, OSX).

 The major drawback is that all those have obscene memory requirements as compared to plan.

 Notice that korganizer, evolution and sunbird can all read/write calendars in a common interchange
 format (iCal). Hence unlike plan, none of them is a dead end.

 * gcc 3.4.6
 * Open``Office 2.0.4 (generally: latest stable release)
 * mozilla -> firefox, thunderbird, nvu
 * subversion 1.3.2
 * maple 10s Rel 6
 * ROOT versions 5.08, 5.12
 * java 1.4.2, 1.5 (default), 1.6

== Known Problems ==
 * problem with multiple gnome sessions if large ~/.Xauthority (=> delete)
 * The '''trash bin on the GNOME desktop''' will always show up empty. Files deleted this
 way are moved to `~/.Trash`, as they should, but GNOME is "clever" and "knows" that this
 directory can only reside on a few well know filesystems, from a hardcoded list. This is an old
 and well known
 problem in GNOME, present on SL3 as well, that also hurts other operating systems and filesystems.
 Notice '''everything you move into the GNOME trash bin und thus into ~/.Trash ''does'' count
 against your home quota even though it won't show up on your desktop'''.
 * ssh-agents keep accumulating
 * DVD-ROM on Dell 380 is limited to 1 MB/s, no cure yet

== Hardware Requirements ==
 * 128 MB of RAM
 * 6 GB /

=== (In)Compatibility List ===
'''Compatible:'''
 * Desktops
  * '''hyade/dryade/satyr''' class (Dell Precision 350, 360, 370, 380)
  * '''nereide/oceanide''' class (ASUS P4T-E, 82850 Chipset)
  * older systems:
   * ASUS P2B-L, 440BX Chipset, PII 350 MHz, Intel Ethernet Pro 100, EIDE disk on PIIX4
 * Servers
  * '''Dell Power``Edge 1850/2850/1950''', including the PERC4 RAID controller
  * '''SUN Fire X4100''', including the LSI SAS1064 RAID Controller
  * '''TYAN S2892 (Storbox)''', including SATA disk on the onboard nvidia SATA controller and
  the '''Areca ARC-1260''' RAID-Controller

'''Incompatible:'''
 * Desktops
 * Servers
  * '''Supermicro X5DP8''' Mainboard (E7501 Chipset), with onboard onboard Adaptec AIC-7902B,
  at least with BIOS 6.00 of 08/02/04
   * reliably hangs after formatting a few GB of filesystem
  * '''Adaptec 2010S''' "Raptor" Zero Channel RAID Adapter (I2O-RAID)
   * no disks recognized by SL 4.3 installation kernel

'''Unknown yet:'''
 * Desktops
  * najade class and earlier systems
 * Servers
  * SUN V65x (E7501 Chipset, Adaptec AIC-7902 ...)
   * IPMI? no bmc driver from intel or sun for linux 2.6...

== Installation Times ==
 * 4.3 without many updates (likely to get worse)
  ||<rowstyle="background-color: #E0E0FF;"> bits |||| CPU / GHz |||| RAM / Type || Disk || Time [minutes] ||
  || 32 || P4 || 3.2 GHz || 1 GB || DDR2      || SATA || 40 ||
  || 32 || P4 || 1.7 GHz || 256 MB || RAMBUS || EIDE || 60 ||


-----
Footnotes