I am getting quite excited about some of the material I have been reading on Common Event Expression (pdf). CEE is a desire to standardise the way that events are described. I can see this being of significant advantage to sysadmins who need to produce large scale monitoring systems.
We already all use syslog-ng or rsyslogd or similar to aggregate our logs centrally, but it would be great to be able to aggregate logs inside our monitoring systems in such a way that when we add servers to our networks, any issues that they raise, in the application layer, or in hardware, are described to monitoring systems in a common and expected way.
If the taxonomy of error handling was equivalent on, say, routing kit as well as desktop systems, this allows sysadmins to deploy complex monitoring systems with less effort. Understand how to handle a mistake with system-X and every single system you deploy from then on benefits from tried and tested monitoring and management.
Its early days for CEE, but I am optimistic about the benefits we could all realise if there was a desire to standardise logging. Looking forward to what happens next.
I am testing out Adaptive Readahead in Linux quite a lot at the minute. ARA offers particular performance improvements to file-reading logic, and should give significant performance wins on database servers.
I now have a stable enough kernel package for Debian users who may want to try it out. The kernel package uses the same defaults as etch, but there’s a version bump to 2.6.21, and of course I have turned on the ARA features!
Download the Debian Adaptive Readahead package and install with dpkg -i
Please post a comment if you try it out and have anything to report.
I was trying to print from a mac to the HP Laserjet 1022n printer. Bonjour could see the printer, but couldn’t find a driver.
All of the blogs I found when googling recommended to plug the printer into the mac directly, let it detect it as a local printer, then plug it back into the network. Frankly, that’s pants.
Just pick the ‘HP Laserjet 5 Series’ gimp-print driver from the drop down. It works fine then.
I have typed this info into several irc privmsgs in the last month, so I’ll write up how to setup ‘friendly’ sip uris with Asterisk.
Firstly let’s look at DNS. Say my email address is abc@example.com. The A record for example.com probably points to example.com’s webserver, so that people who skip the www can still see your website. Therefore, if you don’t run Asterisk on the web-server, how do you redirect packets to your voip server ?
The answer is the service (SRV) record. If example.com’s voip server was ‘voip-in.example.com’, your SRV record would look something like this :
_sip._udp IN SRV 1 0 5060 voip-in.example.com.
You then need to configure Asterisk to handle the sip packets properly. The default domain on this asterisk box is probably ‘voip-in.example.com’. Fortunately, multi-domain support is pretty easy, you just have multiple ‘domain’ lines, thus :
domain=example.com,visitors
…which would send requests for abc@example.com to the ‘abc’ extension in the [visitors] context in your dialplan.
The easy thing to do here is to just force requests to for the email-form sip uris to ‘goto’ the right section of the dialplan in your ‘normal’ phone dialplan, e.g.
[visitors]
exten => abc,1,Goto(default,1001,1)
This avoids lots of duplication. Ensure that your default/unauthenticated sip contexts do not allow access to your pstn gateway!
Geoff Huston produces a report that quantifies the scarcity of IPv4 addressing resources. He has changed the prediction model to a polynormal system, which much more accurately maps onto historical resource demand patterns.
The result isn’t good news; the IANA pool of addresses free for allocation to RIRs is starting to look frighteningly scarce – boxing day 2009 will be the day that IANA’s stock is gone.
Though I think that ipv6 is a policy and political nightmare, I don’t think greenfield network deployments should be made without some thought to v6. Ensure all new purchases for networking gear (load balancers, firewalls, routers, managed switches) all support v6 addressing. Start to ask your upstream networks if they have a v6 transit product.
More importantly, think about conserving the life of v4. We have brought v4 from the point of extinction before with CIDR and NAT overload. I’m now part of an effort, working hard to understand whether the legacy class-E space can be reused for any unicast applications. It’s time to put pressure on the holders of legacy /8s to free them up and return them to IANA.