VPS Hosting Stuff

Introduction:

In general csf is giving good compatibility with cpanel servers . But in a vps (openvz or Virtuzzo) the csf configuration is something different.

Sometimes you may get an error as follow after the csf installation in vps

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Error: iptables command [/sbin/iptables -v -A LOGDROPIN -p tcp -m limit --limit 30/m --limit-burst 5 -j LOG --log-prefix 'Firewall: *TCP_IN Blocked* '] failed, at line 196

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So how to resolve this issue. Let us do it as follows,

There are two steps to configure the csf in vps

i)Main vps server ( The host server ,in which the vps nodes are running) configuration

ii) Vps node configuration.

Main vps serverconfiguration

Before starting the csf installation in a node login to the main server (host server) and check whether the following modules are inserted in to the kernel

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ipt_conntrack
ipt_LOG
ipt_owner
ipt_state
ip_conntrack_ftp
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You can check it as follows

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# lsmod |grep -i <module-name>
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If not please insert these modules into the kernel.

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#modprob <module-name>
eg: modprob ipt_conntrack
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Now add these modules to iptable configuration as follows.

———–
# vi /etc/sysconfig/iptables-config
Add the following in this file
IPTABLES_MODULES=”ipt_conntrack ipt_LOG ipt_owner ipt_state ip_conntrack_ftp”
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Now edit the vps configuration file from /etc/sysconfig/vz-scripts/ Let 101 is the VEID, add the above inserted modules in to the IPTABLE section in this configuration file.

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# vi /etc/sysconfig/vz-scripts/101.conf
IPTABLES=”iptable_filter iptable_mangle ipt_limit ipt_multiport ipt_tos ipt_TOS ipt_REJECT ipt_TCPMSS ipt_tcpmss ipt_ttl ipt_LOG ipt_length ip_conntrack ipt_state
iptable_nat ip_nat_ftp ipt_owner ip_conntrack_ftp”
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Here we completed the main vps server configuration . So now reboot the child node (not main server) as follows

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# vzctl restart <veid>

eg: vzctl restart 101

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ii) Vps node configuration.

Now ssh /enter your child vps node

Now download and install the csf . You can download the csf fromhere

Before restarting the csf let us do some configurations as follows , Edit the file /etc/csf/csf.conf .Then set the following variables

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ETH_DEVICE = “venet0″ #from ifconfig you can see the n/w device
MONOLITHIC_KERNEL = “1″
VERBOSE = “0″ # will disable the verbose output during start
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Now start the csf and lfd .

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/etc/init.d/csf start

/etc/init.d/lfd start

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Note: If it is cpanel server go to whm and configure the firewall settings

Enjoy it

Nice discussion going on slashdot.org about performance differences of xen and openVZ.

An anonymous reader writes Compared to an operating-system-level virtualization technology like OpenVZ, Xen — a hypervisor-level virtualization technology that allows multiple operating systems to be run with and without para-virtualization — trades off performance for much better isolation and security. OpenVZ’s performance advantage due to running virtual containers in a single operating system kernel can be significant. A performance evaluation study (PDF) done by researchers at the University of Michigan and HP labs provides insight into how big a performance penalty Zen pays and what causes the overheads (primarily L2 cache misses).

From the report: “We compare both technologies with a base system in terms of application performance, resource consumption, scalability, low-level system metrics like cache misses and virtualization-specific metrics like Domain-0 consumption in Xen. Our experiments indicate that the average response time can increase by over 400% in Xen and only a modest 100% in OpenVZ as the number of application instances grows from one to four… A similar trend is observed in CPU consumptions of virtual containers.”

Read more from : http://slashdot.org/article.pl?sid=07/05/15/019251

OpenVZ (the basis for the commercial Linux platform Virtuozzo) and Xen could be viewed as competing VPS platforms, however, the truth of the matter is that they are very different - read on to find out how the OpenVZ and Xen VPS platforms work, how they differ, and why the choice of OpenVZ or Xen is an easy one to make.

OpenVZ Virtualization

openvz vps hosting

OpenVZ is an operating system-level virtualization platform based on a single Linux kernel which has been modified to support multiple Linux virtual environments (more commonly referred to as virtual private servers).

The modified OpenVZ kernel isolates the file system, memory, and processes for each virtual environment, providing OpenVZ VPS administrators with full root access and all of the commands normally associated with a dedicated server.

Xen Paravirtualization

xen vps hosting

Xen is a paravirtualization platform which is very similar to hardware emulation. Paravirtualization works by creating an interface between the virtual environment’s operating system and the hardware which queues and responds to operating system requests from operating systems modified to interact with the paravirtualization interface.

This key difference from operating system-level virtualization allows Xen VPS administrators to modify their kernel modules, utilize swap space to meet memory allocation demands, and watch their Xen virtual private server’s boot process as Linux mounts virtualized devices.

Key Differences: