I've been working on one of my other blogs trying to get the preload function working in WP Super Cache. It seems pretty straight forward, but for some reason there are a couple of issues.
First, the timed preload of cache files does not seem to work reliably. I had set it to 30 minutes with email notifications, and it would only go once, or twice at the most. Beyond that it would just not do anything at all. Once, I even turned off the scheduled preload and it did it anyway!
Secondly, even when doing a manual preload of the cache, the preloaded files get removed from the cache even though the description clearly indicates that supercache files from the preload will not be removed by the garbage collection. I even went so far as to disable the GC with the same result.
I've created a forum post with the hopes of getting some help. I'll keep this updated as things hopefully progress...
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On my hobby blog PortlandBrewpubs.com I have a listing of all the brewpubs in the Portland area. The list is pretty long (yes, its Beervana!) and quickly became a management headache to keep everything looking uniform. I was looking around for way to standardize all my posts and ended up fixing up my own solution that was both free, and supportable as near as I can tell.
I started using Custom Fields in WordPress for all of the interesting bits of information in my posts to keep it standard. I have one for all the useful Pub stats. Street address, website, phone number, hours, etc. This way I can fill in a value for each field and know I'm not missing anything. I then use the very handy plugin Get Custom Field Values to display the fields in my Post. In the beginning I had all the formatting for every post right in the post body. This worked pretty well until I wanted to change the layout, at which time I realized it was a pain to update my site. I would then have to go to every post and replace the body of the post content. With over 40 pubs in town I didn't want to have to do that every time. I had to strategize a way to avoid this moving forward.
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I've been a little out of touch with this blog in the last month or so. Ever since Thanksgiving things have been crazy, especially at work with the busy season.
Over the last year we have made some great efforts to dramatically increase our stability as well as availability by increasing redundancy to remove single points of failure. This was on many levels including the networking layer by introducing an HA firewall pair, and an HA load balancer pair. We also built out our server infrastructure by implementing 3 web servers for the load balancing, as well as clustering our database hardware and our application server hardware. All of this was intended to be able to easily handle the load of the retail busy season, between Thanksgiving and New Year's weekend. To be able to really know how much we could handle we wanted to load test the infrastructure top to bottom.
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After getting MRTG setup and running in my MRTG Virtual Appliance as I call it, I started setting up all my networking devices for monitoring. One of the devices I really wanted to poll some more advanced data from is our Load Balancer. What I really wanted to be able to see was the number of concurrent connections to the LB and each of the Virtual Servers if possible. This proved to be much more complicated than I had anticipated.
My first problem is that my SNMP software in Ubuntu was not configured correctly. By default the SNMPd was looking for /usr/share/snmp/mib to load the mib files. In the version of Ubuntu that I had the path was /usr/share/snmp/mib2c-data so I had to update the snmp.conf file. Once I did that then SNMP was able to correctly load all the add-on MIBs so that I could have the OID definitions load correctly.
My second problem was the the MIB file that I had gotten from the web was incorrect, or more to the point it was outdated. The search that I did for F5 MIBs returned many hits, but the one that I went to for most of the information I started with was a nice post at vegan.net. Unfortunately, I didnt realize that this was really out of date. As a result the LOAD-BAL-SYSTEM-MIB.txt is invalid with the software version that my F5 is running and fails the OID lookups.
My F5 is hosted so I dont have direct access to the device. I was able to get the hosting company to grab the MIB files from the filesystem of the F5, and then I put them into my /usr/share/snmp/mib2c-data directory. After that my MRTG graphs for Virtual Server connections started working. One mistake that I made in this process was only putting some of the MIB files on my machine. Do yourself a favor and just get ALL the MIBs and load them to your SNMP MIBs folder.
I found a nifty script here called Buils_mrtg_cfg_for_virtual_servers.pl.txt that was able to do an snmpwalk and get all the information about my Virtual Servers that I needed to get current connections and bandwidth on a per VS basis. From there MRTG was up and running with some pretty good stats about concurrent connection rate and bandwidth utilization across all my domains.
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Over the last couple of weeks I have been working to build an MRTG server in our VM environment. I wanted it to be very lightweight for CPU, RAM and Disk storage.
I've used MRTG quite a bit before and it can sometimes be tricky getting everything worked out just right so that it runs without babysitting. I finally got a pretty good install going and thought I would share it up here for anyone who might find it useful.
This is an MRTG Virtual Appliance that is running on Ubuntu Server for Virtualization. The install is very compact with just a 2gb virtual disk, 1 cpu and 512MB of RAM. You can download the MRTG_Appliance here. Total file size is ~430MB.
MRTG is setup and configured as well as lighttpd as the webserver. The server is configured for DHCP and SSH is enabled for console management. There is no GUI but there is a configuration page linked from the default webpage.
This is a first run at creating an Appliance/OVA file for me, so I'm sure I have missed some steps. I will update this page as well as the download file as any issues are identified.
Let me know how it goes so we can make it better!