Bandwidth

Here is the basic of it. Bit (connection) vs Byte (transfer or storage) The measurement of the network connections is done in bits as opposed to data transfer and computer storage which we measure in bytes. Eight bits is the equivalent of one byte. Thus a 100Mbps (Mega bit per second) can handle 12Megabytes of data per second. Units of measurement K Kilo 1,000 one thousand M Meg 1,000,000 one million G Gig 1,000,000,000 one billion T Terra 1,000,000,000,000 one trillion To get a meaningful estimate of throughput, divide the data connection pipe by eight. i.e. A 56K modem can download at a maximum throughput of around 7KiloBytes per second. Dedicated Pipes (Data Centers) Pipe Data connection size (Bits per second) 10Mbps 10Mbps Maximum transfer rates of 1.25MegaBytes of data transfer per second. 100Mbps 100Mbps Maximum transfer rates of 12.5MegaBytes of data transfer per second. 1Gbps 1Gbps Maximum transfer rates of 125MegaBytes of data transfer per second. Bandwidth, How to Choose? Which is better, (a) a fixed 2,500 Gigs of transfer per month (a shared 100Mbps pipe, by 20 servers) (b) an unlimited 10Mbps pipe? Of course, (a) hands down! Why? A 10Mbps pipe can handle a MAXIMUM throughput of 3,240 Gigs of data transfer per month (30 days). Since almost ALL traffic occurs on some sort of bell curve, your server will start to suffer LONG before it ever reaches that theoretical limit. Think Monash car park during peek times. At 50% of your theoretical throughput limit, you would have already started suffering long delays/lag time during your peak hours of operations and it is time to move to a bigger pipe. As a rough idea... A 10Mbps connection can handle websites of up to 1,600 Gigs of transfer a month. A 100Mbps connection can handle websites of up to 16,000 Gigs of transfer a month.


Install VMware tools on CentOS 5.5

Make sure GCC and kernel headers are installed
yum install gcc kernel-devel
Mount your vmware tools .iso YMMV
mkdir /media/cdrom
mount /dev/cdrom /media/cdrom
Extract the VMware tools archive to our home dir
tar -zxvf /media/cdrom/VM* ~/
Run the installer
~/vmware-tools-distrib/vmware-install.pl
You should be good to go using the defaults for everything. Reboot and your done.


Remove all files unpacked from tar (.gz) archive

tar -tf <archive .tgz> | xargs rm -r


Disable IPv6 on CentOS 5.5

1. Edit /etc/sysconfig/network and set “NETWORKING_IPV6? to “no” * This still loads the module but IPv6 is administratively disabled. Run the next command to prevent loading the ipv6 module 2. Then add the following to /etc/modprobe.conf : * alias ipv6 off * alias net-pf-10 off 3. Now reboot the machine.


Ubuntu Version and type (32 or 64 bits)

Current installed version of Ubuntu
cat /etc/issue
To know if you have installed Ubuntu 32 or 64 bits:
uname -m
If it shows i686 or i386 it is the 32 bits version. If it shows x86_64 it it is the 64 bit version. If the CPU is a 32bit CPU you can only install the 32 bit version of Ubuntu. If the CPU is a 64bit CPU you can install the 64 or 32 bit versino of Ubuntu. To know if the CPU is 32 or 64 bits:
grep -w lm /proc/cpuinfo
If we see lm in red it is a 64 bit CPU.
sudo lshw | grep “description: CPU” -A 12 | grep width
This should output the CPU width (32 or 64bits)


VMWare Server 2.0 on Ubuntu 10.04.2 LTS

So I got stuck getting VMWare 2.0 Server to install on Ubuntu 10.04.2 LTS with Kernel 2.6.32-32-generic-pae. You will need to patch the vmware installer to get this to work. Download VMware-server-2.0.2-203138.i386.tar.gz No need to unpack it. Grab this patch. (Use the 1.5 one) https://github.com/raducotescu/vmware-server-linux-2.6.3x-kernel/tree/release-1.5 Unpack the patch into the same folder as the VMware download. Run the following
# fix headers
aptitude remove linux-headers-$(uname -r)
aptitude install linux-headers-$(uname -r)
 
# remove line 269-270 from vmware-server-2.0.x-kernel-2.6.3x-install.sh
sed -i.bak 269,270d vmware-server-2.0.x-kernel-2.6.3x-install.sh
Then run the patch.
./vmware-server-2.0.x-kernel-2.6.3x-install.sh
This worked perfectly for me.