Today, I'm going to introduce the concept of mount
points. Mount points are, in essence, folders in which external filesystems are
mounted (their contents are dropped into that folder). We'll be going into that
in a bit more detail in just a second. First of all, the obligatory Wikipedia
definition:
A mount point is a term used to describe where the
computer puts the files in a file system on Unix-like systems. For example,
many modern Linux distributions automatically mount the CD drive as /mnt/cdrom,
so the contents of the CD drive will appear in the /mnt/cdrom directory. A
device can be mounted anywhere on the directory structure. Normally only the
root user can mount a new file system but systems are often configured so that
users may mount pre-set devices. A file system can be mounted by running the
mount utility.
Windows, OS/2 and other operating systems that have
their heritage in DOS and the old days of the IBM PC, use a drive letter
structure to access different devices on the system. I'm sure you're aware of
the idea of the C drive under Windows.
Well, Unix-like operating systems don't work anything
like that, I'm afraid.
Let's have a quick example. I've got a 512 MB USB stick
and I plug it into my PC running Linux. Behind the scenes, the operating system
does the following:
Creates a folder called /media/PETER512 (PETER512 is
the volume name of my USB stick).
Mounts the USB stick's contents inside this new folder
Fairly simple. So what does it actually do when it
mounts the contents? Think of it as taking the contents of the device and
dropping them into that folder. Now, if you browse to that folder, you can read
and write the contents of the actual device, just as if it was a normal folder
on your hard drive.
The folder (which is the mount point - the point where
that device is mounted) can be anywhere, but it's a convention that you use
/media or /mnt. Equally, it doesn't have to be a USB stick. CDs, DVDs, network
drives, removable hard drives, even .iso image files, can be mounted so you can
access them and interact with them.
And finally, a quick command line practical exercise.
You will need to know the device string of whatever you want to mount, which
unfortunately makes this process a bit geeky and difficult. In this example,
I'm using /dev/sda1 (which is what most USB devices are if you have IDE hard
drive).
In most cases, you also need administrator/root
privileges to mount and unmount.
# mkdir /mnt/mymountpoint
# mount /dev/sda1 /mnt/mymountpoint
When you're done, you can unmount the device with
umount (optionally, you could also rmdir the folder if you don't need it).
# umount /mnt/mymountpoint
Peter Upfold - http://peter.upfold.org.uk/
Peter Upfold is a technology enthusiast from the UK.
Peter’s interest in Linux stems back to 2003, when curiosity got the better of
him and he began using SUSE 9.0. Now he runs Linux Mint 9 on the desktop, runs
a CentOS-based web server from home for his personal website and dabbles in all
sorts of technology things across the Windows, Mac and open source worlds.
Procedure
For tp, the transport directory must fulfill the following requirements
(depending on the operating system):
UNIX
In a transport network, there must be a single physical transport
directory that can be reached from each host with the same path.
In UNIX systems, this directory can be a soft link, pointing to
the correct transport directory or mount point.
You must store the chosen path in two parameters:
- Parameter transdir for the transport
control program in the Transport Profile
- Parameter DIR_TRANS for the SAP System in
the instance profile
The default value for the transport directory is /usr/sap/trans in UNIX.
Windows
Transport groups comprised of Windows systems, or of Windows and
UNIX systems are supported.
For more information on creating a heterogeneous transport group,
see Transport Control under Windows.
SAP allows you to name a central transport host on the Domain Name
Server that is valid for all Windows systems.
For more information on specifying a central transport host on the
domain name server, see Specifying the Central Transport
Host.
Each transport group must have a single physical transport
directory that can be accessed by all machines.
This directory is described by the parameters:
- transdir (transport profile)
- DIR_TRANS (instance-specific
profile)
If you have entered a transport host on the domain name
server, the directory is under \\$(SAPTRANSHOST)\sapmnt\trans by default.
Otherwise it is under \\$(SAPGLOBALHOST)\sapmnt\trans .
The transport directory is described by the following parameters:
- SAPTRANSHOST
Name of the host configured as the central transport host on
the domain name server
- SAPGLOBALHOST
Name of the host on which the central system is installed
- sapmnt
Global share that points to the \usr\sap file tree on
the central instance
Note the different naming conventions used for the
parameters transdir and DIR_TRANS:
The path entered for the parameter DIR_TRANS does not end
with a "\", whereas the path entered for the parameter transdir does end with a
"\":
DIR_TRANS = T:
transdir = T:\
The DIR_TRANS profile parameter that you set
and the parameter transdir in the transport profile must point to the same transport
directory.
IBM eServer iSeries
In a transport network, there must be a single physical transport
directory that can be reached from each host with the same path.
In iSeries systems, this directory can be a soft link, pointing to
the correct transport directory or mount point.
You must store the chosen path in two parameters:
- Parameter transdir for the transport
control program in the Transport Profile
- Parameter DIR_TRANS for the SAP System in
the instance profile
The default value for the transport directory is /usr/sap/trans in iSeries.
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