I’m checking out Wimp as a substitute to Spotify. My Wimp stopped working yesterday and refused to start because of ‘wrong ELF’. It turned out my Adobe air installation somehow was in 32bit, I don’t know how/why it initially worked (though 32bit apps usually work fine on 64bit Ubuntu thanks to 32bit libs) .
Anyway I came over a 64bit compiled Adobe Air package at launchpad, it installed fine and I could reinstall Wimp again.
Howto forge has been helpful when running Xen on Debian Lenny.
I’m looking at upcoming Debian Stable, Squeeze, which is at Beta1 for the moment. xen-orchestra.com gave me some hints when xen complained about missing hypervisor.
I’m configuring rkhunter on a new Debian Lenny setup for production. The rkhunter that comes with apt in Lenny complains about Exim, proftpd, openssl, gpg and openssh being ‘out of date, and possibly a security risk’ . I assume it’s partly because Lenny has been around for a while now, and packages aren’t shiny new versions, but I do trust the Debian security team so I’m whitelisting the apps in question for now. The issue has already been discussed at bugs.debian.org .
I’m optimizing some scripts that split our apache logs each night. I gotta admit Apache’s ‘split-logfile’ script written in perl is a LOT faster than doing it via f.example bash . But splitting up a log file with more than 2000 vhosts resluted in the script crashing. I had to up my ‘open files’ limit with :
# ulimit -n 4096 #
http://www.debian.org/doc/manuals/securing-debian-howto/ch4.en.html
http://httpd.apache.org/docs/2.0/programs/other.html
In the process of upgrading our server where mail for customers where being stored I had to take down the system. One thing is to give thousand of users downtime, they can (must) live with it, as long as you for instance do it during nights or so. An other thing is incoming mail, the system should be able to receive mail 24/7 at least as long as one have more than 1 incoming MX .
Normally Exim is run by the switch -bd -q5m, depending on the configuration in exim.conf Exim usually tries to deliver mail instantly and (ref. -q5m) a queue runner goes through the queue every 5 minutes and may or may not retry delivery of mail hanging in the queue (it may not retry mail where ‘retry time’ has not been reach) .
In exim.conf you may add the directive:
queue_only
meaning that for each incoming mail exim will queue the mail and not try to deliver it at once. Mail is then picked up by the queue runner process and delivered later.
By using this directive and by stopping exim and starting it manually with out the queue runner process:
exim -bd
I was able to queue all incoming mail at our MX and could do what I needed to do with the server where mail is delivered (that is for local deliveries) which in my case was about 3 hours of downtime.
When done I removed the queue_only directive and restarted exim with the queue runner again and everything was well 🙂
Sources:
exim.org
Upon testing the performance of a raid 6 array with 13 disks i wanted to check read/write performance, an easy way to do this fast on Linux (Debian) is simply using ‘time’ and ‘dd’:
bakis:/var/raid6volume# time dd if=/dev/zero of=./testingtransfer bs=16k count=16k 16384+0 records in 16384+0 records out 268435456 bytes (268 MB) copied, 1.48474 s, 181 MB/s real 0m1.513s user 0m0.008s sys 0m1.456s bakis:/var/raid6volume# time dd if=./testingtransfer of=/dev/null bs=16k 16384+0 records in 16384+0 records out 268435456 bytes (268 MB) copied, 0.156663 s, 1.7 GB/s real 0m0.159s user 0m0.004s sys 0m0.160s bakis:/var/raid6volume#
The ‘read’ test above isn’t real since the file has been cached . But a rsync is working in the background so I couldn’t umount /var/raid6volume for this example.
Initially I was doing this to test performance over nfs for the same array, one has to umount / mount the share between each test to make sure nothings in the cache.
Working with nfs, tuning wsize and rsize on the client side also gives a lot better performance (at least in my case), see the link bellow for more info.
I got these hints from debianhelp.co.uk
I still need sun’s java plugin to access my internet bank. The recent Ubuntu 10.04 (Lucid Lynx) have removed sun packages from the official repository. But you can still quite easily install Sun java plugin by :
sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner" sudo apt-get update sudo apt-get install sun-java6-plugin
source: beeznest.wordpress.com
Nice command to find how much ram my graphics card has. Use ‘lspci’ to get the pci id and throw it back to lspci like this:
joar@juno:~$ lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 09) joar@juno:~$ lspci -v -s 00:02.0 00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 09) Subsystem: Lenovo Device 3a02 Flags: bus master, fast devsel, latency 0, IRQ 30 Memory at f4000000 (64-bit, non-prefetchable) [size=4M] Memory at d0000000 (64-bit, prefetchable) [size=256M] I/O ports at 1800 [size=8] Capabilities: <access denied> Kernel driver in use: i915 Kernel modules: i915 joar@juno:~$
Ethtool is a great tool you can use to adjust several settings at your NIC.
It’s especially great to detect if a cable is connected or not. Say you’ve got 3 NIC’s at your server, your hooking up one to the switch and wondering did I hook up eth0, eth1 or eth2 now (?)
# ethtool eth1 Settings for eth1: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Advertised auto-negotiation: Yes Speed: 1000Mb/s Duplex: Full Port: Twisted Pair PHYAD: 0 Transceiver: internal Auto-negotiation: on Supports Wake-on: umbg Wake-on: d Current message level: 0x00000007 (7) Link detected: yes
As we can see ‘Link detected: yes, we’ve got a winner.
Note: you have to bring up the interface with :
> # ifconfig eth1 up
or else ethtool will say the link is not detected even if a cable is attached.
I’m looking at ifolder, and during installation on my test server I spent some time trying to get my head around the ifolder documentation regarding using .pem certificates with apache2. They explicitly say you have to export your self signed certificate as .pem with ‘ca certificate only’, on my OpenSuse test server /var/log/apache2/error.log kept on giving me
Init: Private key not found
This post gave me a hint on how to resolve this. Exporting the certificate as specified in the ifolder administrator documentation as ‘ca certificate AND the private key’ solved it all.