A special extended edition of Tech Messages for 2012-10-05 through 2012-10-25:
I have a fairly lightly loaded MySQL server with a few tables that are updated every five minutes. Other than these updates, there are very few queries run against the database. The data is queried just a few times per month. Ever so often, one of the more complicated queries will result in the process getting hung in the "copying to tmp table" state. To be honest, the queries that get hung aren't even that complicated. Usually there's one or two joins, a
GROUP BY, and an
So far, when a process gets stuck in this state, I find that killing and restarting the process does not clear up the problem. I've changed my recovery method to killing the process, issuing a
FLUSH TABLES, and restarting the process. This has worked fine for me, but I've heard of others that had to resort to restarting the daemon.
A special extended edition of Tech Messages for 2012-05-28 through 2012-08-24:
Here are a few tips that might be helpful if you are having trouble accessing your Cisco router or switch via the web server.
- Make sure you have the right password! This is pretty obvious, but it's definitely the first thing worth checking.
- If you're using
aaa new-model, you will need to tell the web server what group to use for authentication:
ip http authentication local.
- In order to make changes to the device, your user will need access level 15. You can set this with the username command:
username slap privilege 15.
- It's a good idea to use HTTPS instead of HTTP if possible. Enable that with
ip http secure-server. You can disable the non-encrypted web server with
no ip http server.
- The web server supports a very basic access list. You can lock your web server down even further by limiting who can connect to it. Use
ip http access-class 9. Remember to set up your access list first!
I don't know why SELinux problems seem so frustrating. The problem almost certainly is related to the fact that there is frequently no error message. This is exactly the problem I ran into while turning up a new Apache web server on Red Hat Enterprise Linux 6 (RHEL6) with SELinux enabled.