Showing posts from December, 2006

lm-sensors on NVIDIA NForce Pro chipset

The modules needed for properly setting up lm-sensors on my Tyan motherboard are: i2c-nforce2 lm85 k8temp And the lowest version of lm-sensors with support for k8temp is 2.10.1. I am still at a loss about reading the output, though. # sensors lm85-i2c-0-2d Adapter: SMBus nForce2 adapter at 2d00 V1.5: +1.81 V (min = +0.00 V, max = +3.32 V) VCore: +1.25 V (min = +0.00 V, max = +2.99 V) V3.3: +3.25 V (min = +0.00 V, max = +4.38 V) V5: +4.97 V (min = +0.00 V, max = +6.64 V) V12: +12.06 V (min = +0.00 V, max = +15.94 V) CPU_Fan: 0 RPM (min = 0 RPM) fan2: 1626 RPM (min = 0 RPM) fan3: 0 RPM (min = 0 RPM) fan4: 0 RPM (min = 0 RPM) CPU Temp: +40°C (low = -128°C, high = +127°C) Board Temp: +36°C (low = -127°C, high = +127°C) Remote Temp: +46°C (low = -127°C, high = +

There is no such thing as coolers for Socket F CPU

There is no such thing as coolers for a Socket F. There isn't enough information on the internet for me to actually say anything that I can vote for, but here is my experience. On my Tyan Thunder n3600B there are two couples of retention brackets. These brackets are screwed around the socket and it is thus possible to use any cooler that is compatible with Socket AM2. Since I was stupid enough to buy a couple of coolers that are too big to fit when placed close to each other (the sockets are a bit too close, but that's what I get for getting an ATX motherboard) I also learned that coolers for Socket AM2 are compatible with Socket 754, and possibly all other recent AMD sockets. After all, it is just a clip and luckily the dimensions of that clip haven't changed much.

Moving around freely in Vim

In Vim, to move the cursor to a location where there is no character, use the "virtualedit" or "ve" commands. E.g., :set ve=all and then move around freely. I always keep forgetting that.

RAID5 on two disks only

I'm building a new server, but since I am a little short on cash I managed to only buy two 500GB Western Digital hard drives. The logical solution would be to add them to a RAID-1. RAID-0 offers no redundancy in case of a crash, and RAID-5 is not possible if you believe what everyone is saying, including this Wikipedia article . The truth is that RAID-5 requires only two drives to operate properly. The way RAID-5 works is that it stores the checksum of all data blocks in a stripe in a checksumming block on the same stripe. So, if you have only two disks you'll get the data of one disk checksummed on the other and they'll go on alternating as per the specification. In other words, by joining my two disks on a RAID-5 I'll get almost the equivalent of a RAID-1. And if you don't believe me, here is how to try it for yourselves. First, create two empty files of about 100MB in size: dd if=/dev/zero bs=100M count=1 of=diskA dd if=/dev/zero bs=100M count=1 of=diskB Bind th

Useful OpenSSL commands for your own CA

Here is a short summary of how I am managing my SSL certificates Edit /etc/ssl/openssl.cnf and add a section for each separate certificate authority, e.g. CA_servers CA_clients, CA_vpn Use a safe umask: umask 077 Generate a private key an unencrypted key (no password needed) openssl genrsa -out key.pem 2048 an encrypted key (with a password) openssl genrsa -aes256 -out key.pem 2048 Create a certificate request: openssl req -new -key key.pem -out req.pem Sign the certificate: openssl ca -name CA_vpn -in req.pem -out cert.pem Optionally add specific extensions to the signed certificate: Prepare a section in /etc/ssl/openssl.cnf like this: [ext_server] nsCertType = server, client Modify the signing command like this: openssl ca -name CA_vpn -in req.pem -out cert.pem -extensions ext_server

NFS Freezes and Jumbo Frames

After trying to use jumbo frames on my newly upgraded network and realizing that one adapter is not enough, I simply left things as they were. Come today, my NFS mounted directories on the server were unaccessible and none of restarting the NFS server (just the NFS server process, not the machine itself) unmounting the directories or trying to mount them again helped. Eventually a little playing around with tcpdump on both the server and client tcpdump -i any port 2049 revealed that the client was sending requests and the server the appropriate responses, but for some reason the responses were not reaching the client. Quickly disabling the jumbo frames on the server ip link set mtu 1500 dev lan and everything was back in order. Conclusion: Jumbo frames are evil. Update: The Gentoo Linux Wiki has a nice tip about jumbo frames and NFS and why it is not good to mix jumbo with standard frames.

Google webmaster tools refuse to verify a Wordpress blog

Google webmaster tools will not verify a site by the file upload method if it does not return a proper 404 code on missing pages. With Wordpress and permalinks enabled, everything is redirected to index.php, which does exist and unless the PHP code itself overrides the return code, the response would be 200. The solution is to simply edit headers.php in the theme and add the following to the beginning of the file: <?php if (is_404()) { header('HTTP/1.1 404 Not Found'); } ?>

64-bit Virtualization on Athlon 64

As quoted on the VMware Knowledge Base , running a 64-bit guest operating system requires one of the following: AMD Athlon 64, revision D or later AMD Opteron, revision E or later AMD Turion 64, revision E or later AMD Sempron, 64-bit-capable revision D or later (experimental support) Intel EM64T VT-capable processors (experimental support) I don't have such a processor so I should stop trying to run a 64-bit system in VMware.

Buying a Socket F Opteron

The server that this blog is running on has served me well. It is running e-mail with SPAM and anti-virus filtering, officially mirroring several OSS projects and it is also serving several web pages. It is doing its job well, but it has been pushed too hard and it is time for a replacement. When putting it together (actually upgrading it from a Slot A Athlon) I had bought an ASUS P4S533-X motherboard which allowed my to go with a cheap Celeron running at 2.4GHz and reuse two of several PC133 512MB DIMMs (buying DDR would have been too much for me at that time). And it has run like that for quite a while. When I decided to upgrade the machine, I decided that I'll buy something that is going to run for a while. So I decided to go with a couple of the new dual core Opteron processors (the HE type) a reasonable TYAN motherboard and four pieces of 512MB DDR2 DIMMs (registered memory is still too expensive). So, it was hard enough to find a retailer carrying all these items in Japan..

Jumbo Frame Troubles

I got a new Intel Pro/1000 XT server adapter, a so-so switching hub ( NetGear GS105 ) and I immediately upgraded my network. Since both the Intel adapter and the switch were jumbo frame compatible, I decided to try that feature out. Ran the following commands on the server (with the Intel adapter): ip link set mtu 9000 dev lan and after a small delay everything seemed to be OK. Ran the same command on my workstation -- an Asus K8V SE Deluxe motherboard with an onboard Marvell Gigabit adapter. The screen froze and after a few seconds the computer rebooted. That's with a vanilla kernel. Gotta be more careful.