November 3, 2009 / 0 Comments
ncftp is a client suite offering a command-line interface to commonly-used File Transfer Protocol (FTP).
To install it in one line simply run the below command. Substitute in the most currnet version for 3.2.3
cd ~; wget ftp://ftp.ncftp.com/ncftp/ncftp-3.2.3-src.tar.gz \
tar zxvf ncftp-3.2.3-src.tar.gz; cd ncftp-3.2.3 \
./configure && make && make install; cd ~ \
rm -rf ncftp-3.2.3-src.tar.gz ncftp-3.2.3
November 3, 2009 / 1 Comment
It’s quite common for a cPanel server to need a larger /tmp partition.
cPanel, by default, creates a loopback device that mounts to /tmp. The default size is only 512MB. This is quite small, especially for shared systems.
Reasons /tmp might become full:
- MySQL operation or Repair requiring temporary space. Keep in mind the /tmp partition must be big enough to support the largest table size on your system. (8GB table would require 8+GB /tmp space)
- PHP sessions consuming space in /tmp
- Rogue scripts living in /tmp
To resize follow these steps:
** Note that this will stop MySQL and will cause service interruption. These commands will resize /tmp to 2GB. If you wish to resize to a greater or smaller size simply change 2048000 to your desired size in bytes.
sed -i -e 's/512000/2048000/g' /scripts/securetmp
ln -s /var/lib/mysql/mysql.sock
If you receive errors stating that /tmp could not be unmounted simply run the following command to identify the PID (Process ID) still using /tmp
Next, kill all processes using /tmp using “kill –9 <pid>”
October 31, 2009 / 0 Comments
Having worked in data centers for the last four years of my life I know that most servers are grossly under utilized. Burning the power to keep servers online that are utilized, on average, five to twenty percent.
Economics, the way they are today, constantly challenges us and pushes us to find new and creative ways to solve problems. Virtualization allows us to provide consolidation for under utilized servers and “pools” resources to allow systems to burst when they need it. Virtualization, in my opinion, is a very green initiative. In this article I will talk mainly about VMware based virtualization technologies.
So what are the benefits of virtualizing your servers?
- Instant ROI – Servers which were underutilized no longer consume power.
- Ease of Management – Restart systems from a central management location
- Dynamic Resource Scheduler (DRS) – VMware technology provides the capability to VMotion servers from one physical system to another when extra resources are needed. DRS even weighs the “cost” of moving the machine to another host machine.
- Capacity Planner – VMware also has utilities to help you plan your virtual environment based on your site’s resource needs. Simply install a utility and let it run for about 30 days. Once the utility has gathered enough data, you will be presented with suggestions
- High Availability (HA) – VMware offers highly-available services. All of your systems will now have the added benefit of HA at the virtualization layer
So, if Virtualization is so GREEN then what are the downsides?
- Initial equipment cost is high
- Use of fast centralized storage (SAN, NAS) is needed; very expensive
- Systems must match architectures (AMD, Intel) to allow VMotion/HA
- Systems must support Virtualization Technology (VT)
If you can afford the initial expense, virtualization will save you money in cooling, power and equipment maintenance costs in the long run. I believe virtualization is a great tool to help reduce datacenter costs. Please remember there are things that should not be virtualized: large database servers, exchange servers and some application servers may be too disk intensive for your environment’s abilities. Consider keeping these systems as physical servers.
October 31, 2009 / 0 Comments
Ever heard someone use the term VM or VPS? About the only thing they have in common is the V in their name.
A VPS (commonly OpenVZ or Parallels Containers) is a Virtual Private Server and usually runs on what is referred to as a “host node” or the main hardware node. VPS systems allow you to dynamically adjust resources without a restart.
A VM (commonly VMware ESX) is a fully paravirtualized system which all hardware is also virtualized. Many operating systems seem to work the best with paravirtualized systems as the hardware is presented as regular physical hardware.
- Full Paravirtualazation
- Virutualizes at the hardware level- most compatible
- Industry Standard
- Can run Windows/Linux/Suse/Novell/OSX all on the same host
- Cannot dynamically scale resources, VM’s must be rebooted to apply new allocations
- Slightly slower than software-level virtualization
- Cost, expensive
- OS level virtualization
- Fast provisioning
- Dynamic resource allocation, no reboots
- Tighter control of space and inode allocations
- Burstable RAM settings
- Only Linux or Windows VPS systems may exist on a single hardware node
- Price, although cheaper than vmware, still pricey. OpenVZ is a safe free version.
There are many different solutions to virtualizing or “chopping” up the resources for a single, large host system. Our winner was Parallels for their ease of installation, dynamic resource allocation and faster performance. Also keep in mind that if you are virtualizing systems make sure to have a good backup plan and spare parts or on-site warranty. One large host system may provide 20-50 virtual systems. An outage is now multiplied by the systems you have running on top of your hardware node.
October 31, 2009 / 0 Comments
Ever wondered why Postini blocked your email? Luckily Postni provides their “Postini Message Analysis” tool to assist in tracking down pesky false positives.
Here’s how to run your message through their analysis tool:
Login to Google Postini’s web interface at https://login.postini.com/ and release your quarantined message.
Open your message in your favorite email client. View your message headers and copy everything from the top down to (and including) the line starting with “X-pstn-addresses:”
Visit the Postini Message Analysis Tool page and paste in the content we copied in Step Two. Press “Analyze Message”
Review your results and see why the message was counted as SPAM.
Another helpful page is Google’s description for what each custom header tag (added by Postini) represents. See this page for more information.