I’ve finished the server migration and everything was successful and only maybe 30-45 minutes of downtime. The old computer I’m using for a server got an upgrade while I was migrating as well. A little faster processor and doubled the memory in it.

I did run into a problem with ESXi, apparently since the motherboard was older in the server ESXi wouldn’t install correctly onto the drive I had in there, and the motherboard also didn’t support booting from USB to install ESXi to a flash drive, as suggested by a few sites. So I scraped the idea for ESXi and installed CentOS 5.4 on the server without any desktop managers and disabled everything except a few essential services, this netted a server using less than 200 MB of memory. Then I installed VMWare Server 2 on it and transferred my VM image over to the server. Although there is more overhead having a complete OS and VM Server for my purposes it should be fine.

Before this week, my server that handles this website was beginning to show signs that it need a fresh start. It’s currently running CentOS 4.4, so I decided it’s time to upgrade. So I grabbed the latest DVD iso from CentOS for 5.4 and installed a clean virtual machine on my desktop. I’ve just finished migrating everything from the old server to the virtual machine. I’ve also done away with the cobbled together mail solution of sendmail, dovecot, and assp I had running in favor of a very nice open-source Exchange-type replacement called Zimbra.

The next step after a couple of days of testing will be wiping the old drive in the old server and installing VMWare ESXi on it. I decided to virtualize to make it easier to upgrade in the future when I decide to build a new desktop. I’ll retire my current desktop and recommission it as the new server and having everything virtualized should make the transition much smoother. I’m hoping downtime will be minimal if any at all.

Samba 4 which is still in development is the file sharing/logon service program used in Linux that looks to replace Microsoft AD (Active Directory) completely. Although some of the features of AD are available in Samba 3 it takes a lot of work to get these working. At work we’ve recently switched our servers over to Linux and use Samba as a simple logon/file server. It took nearly a month of work to get everything right. The biggest feature missing from Samba 3 is group policies, to work around this we have very long logon scripts. With Samba 4 group policy will be implemented that will make everyone who uses Samba with Windows clients lives easier. No release date has been set but the developers are contemplating releasing a version for those who just want to use Samba as an AD replacement.

Source: Computerworld

InfoWorld has an interesting article about a new upcoming trend in datacenters; using DC power instead of AC. The whole idea behind this being is that as much as 50% of the energy consumed in datacenters is wasted in the AC to DC conversion. The typical path of electricity is AC from power company to racks, then converted to DC then back to AC by a UPS, then in the server power supply converted back to DC for the internal electronics. Each conversion loses a little energy but multiply that by the amount of servers and the loss starts to add up.

The solution is to forget AC all together and run DC directly to the servers. HP, IBM, and Sun are all starting to make their servers with optional DC power supplies and trying to get a standard wiring, voltage, and connector ratified. This move will help companies with limited space expand their datacenter. This is because the energy lost in the conversion from AC to DC and back is released as heat, so the fewer conversion the less cooling needed the more servers you can pack into a datacenter.

For those who don’t know SSH – Secure SHell – is a secure way of remote administration of a server through the command line. This was first used in Unix servers but has made it’s way to Linux and Windows, thanks to open source software.

There is also a different way to use SSH, to make a secure tunnel between a client and server for transferring files. This is known as SCP. The biggest downfall with SCP is that it relied on SSH which by nature was slower because of the computation of the encryption. Now since machines have been getting more powerful, and bandwidth getting faster this downfall is prominent. So the Advanced Computing Group have made improvement to the core of SSH. These improvements were to the flow control buffers, the main bottleneck of the SSH protocol. The new implementation of HPN-SSH now defines the buffers at run-time, meaning the buffers can be increased as long as the link between the server and client is healthy.

The Advanced Computing Group claims to be able to improve the throughput by as much as 1000% just by increasing the buffer size. The group also made available patches to the popular OpenSSH software. I have yet to try this patches but as far as I can tell this looks to be very promising.

Source: HPN-SSH
Patches: OpenSSH with HPN-SSH patches