Zulus Tips

This story begins about 3 months ago, when we have received first server from new Dell’s server line (PowerEdge 1950/2950). That server was a Dell PowerEdge 1950 with one Dual Core Xeon 5110 and two SATA drives connected to integrated controller. That server (in my mind) may be a good replacement for old PowerEdge 850 servers line. In a few weeks after first server delivered to our customer we have noticed about poor IO performance. I have made a few tests with bonnie++, and tests results was very terrible. There was about 30% difference in IO peformance between Dell 850, Dell 1950. Even my home PC with IDE drive was faster.First i have changed OS from FreeBSD 6.2 to Debian testing/unstable - results was same. Googling was a second step but there is not a lot of info about Dell 1950 performance. I have found only 2 posts on boards, but that posts was without replys. With all that info (bonnie test results and two posts on boards) i have write e-mail to Dell. In their reply they asked my to perform some tests with IOMeter using attached profile. Here is some info about test systems:

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It’s not a secret that POP3 (Post Office Protocol) is unsecure protocol. All data, including passwords (!) between POP3 server and PC is going in plain text. POP3, like some other protocols (telnet, ftp, etc) absolutely not resistant to sniffing attacks. Even if you sure that your network or PC is secure you can’t trust your ISP network, that potentially can be compromised. Below you can find how-to secure your POP3 server in few easy steps. This how-to is actual for people who can’t or don’t want to change their POP3 server software, but want be secure.

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In next few days i will go to business trip to Amsterdam. Flight time is about 3.5 hours, so i will have chance to test my new PDA Battery. I have a few ideas how to spent flight time, and i descided to watch few movies. Following short how-to will help you encode movies for your PDA.

To encode movies you need mencoder (from MPlayer package) and at least xvid and mp3 codecs. I have this codec packages installed on my desktop:

libavcodec0d
libxvidcore4
w32codecs

Before start encoding you need to note few parameters:

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Here is easy way to find all broken symlinks:


for i in `find / -type l`; do [ -e $i ] || echo $i is broken; done

Some time ago i have found very interesting patch for FreeBSD kernel. Patch was originally posted by Andre Oppermann in freebsd-current maillist. That patch allows dynamically change TCP send and receive buffer sizes. However Andre posed version only for FreeBSD CURRENT, so i have make note to try patch as soon as i have chance to install CURRENT. But today, my colleague told me that he found version for 6.x, and i have spent last few hours for patching & testing. As i wrote before, patch allows dynamically change TCP buffer size. Using that patch you can save a lot of kernel memory, because you don’t need to set big values for socket buffers. TCP session will start with a small buffer size and grow to match network conditions. Andre showed about 1000% better performance in his tests.
Below you can find my test results.

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Good news! FreeBSD 6.2 just released. I have a lot of systems with RELENG_6, FreeBSD RC1/RC2. I have use 6.2 in production last few months, and has only few problems with Broadcom NetXtreme II (bce) and DELL PERC 5.

Please note, RELENG_4 and RELENG_6_0 is near EOL now, so time for upgrade is come ;-)

Here is official announce:

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