Between 7:00 and 7:45 PM Pacific time Thursday night (March 11), we received two reports of slow or nonexistent network connections to sites on our servers.
Our automated monitoring systems didn’t detect any general problems, so the majority of customers were certainly unaffected — but we suspect that one of the “Internet backbones” between the affected customers and our data center had high packet loss during that period.
Both customers reported that the problem resolved itself by 7:45, and we haven’t received similar reports since, so there does not appear to be be an ongoing problem. We’ll continue to monitor it closely.
If you use a MySQL database with large tables, it’s possible to accidentally run queries that try to sort millions of rows (usually through some kind of programming error, such as an “unconstrained table join”).
Those runaway queries can slow down the MySQL server for many minutes on end, causing performance problems.
To prevent the worst of that, we’ve set the max_join_size setting to 1,000,000 on our MySQL servers.
Read the rest of this entry »
We keep coming across WordPress customer sites that have hurt their performance by switching from the “WP Super Cache” plugin we recommend to a newer plugin named “W3 Total Cache”. Unfortunately, their site often ends up being far slower after switching to W3 Total Cache.
If you care about the performance of your site, please stick with WP Super Cache unless you have a very good reason to switch. It works, and it works well.
Some people tell us that W3 Total Cache works just as well if it’s properly configured, and they may well be right — but it seems like it’s difficult to configure properly. Our experience is showing that it’s easy to get wrong, and performance ends up suffering. WP Super Cache makes it easy to get great performance.
The “calculon” Web server will be restarted at 11 PM Pacific time tonight (February 19). This will cause a five-minute interruption of Web and e-mail service for customers on that server.
Other servers will not be affected, and incoming mail will only be delayed, not lost.
We apologize for the problem and for the short notice: the restart is necessary to replace a disk in the RAID array.
Update 11:03 PM Pacific time: The restart was completed with less than 3 minutes “downtime”.
The “bender” Web server experienced intermittently high load between about 7:40 and 10:15 AM Pacific time this morning, February 18. This resulted in slow or even inaccessible Web sites on that server. (Some e-mail was also delayed before being properly delivered.) Other servers were not affected.
This server had similar high load symptoms (but much more briefly) earlier this week. We took some steps to reduce the load then, but it appears those weren’t sufficient. We’re now taking much stronger action to ensure that this does not happen again.
We sincerely apologize to customers affected by this problem. We don’t consider it normal or acceptable, and we will make sure this isn’t a recurring issue.
Our business offices will be closed on Monday, February 15 to observe the US legal holiday. As always, we’ll provide same-day support for time-sensitive issues via our ticket and e-mail systems. However, questions that aren’t time-sensitive (including most billing matters) may not be answered until the next day, and telephone support (via callbacks) will be available only for urgent problems.
After upgrading our systems to PHP 5.2.6, we received reports of an incompatibility with Joomla. Some URLs do not work when Joomla is configured to use “Search Engine Friendly URLs”, but to not have “Use Apache mod_rewrite” turned on.
We’ve investigated this, and it’s caused by Joomla assuming that PHP has a bug that makes it work incorrectly, when in fact it’s supposed to work differently (and is clearly documented to work differently). Older versions of PHP had this bug, but the new version doesn’t.
To help our customers work around this, we’ve “patched” PHP to intentionally reintroduce the old bug for now, thus keeping it “compatible” with Joomla. If you were having trouble with Joomla’s “Search Engine Friendly URLs”, it should be fixed.
We’ll provide more technical details (and a more robust long-term solution) in the near future.
Update: We’ve also reported this problem to the Joomla developers and suggested a solution.
Due to software updates on our servers, Web hosting customers will experience about seven minutes of scheduled maintenance downtime between 11 PM and 1 AM Pacific time starting on one of the following nights, depending on which server your site is on:
- Thursday, February 4 (servers beginning with the letter “L”, such as “lrrr”)
- Friday, February 5 (all other servers beginning with letters “F-Z”, such as “farnsworth”)
- Saturday, February 6 (servers beginning with letters “A-E”, such as “amy”)
Read the rest of this entry »
We’ve got a lot of customers running WordPress, and we definitely recommend running WP Super Cache to improve performance. It can help dramatically!
But recently we’ve seen a number of our customers getting hammered by a ton of requests from FeedBurner. Usually the request is of this form:
/somepost?utm_source=feedburner&utm_medium=feed&utm_campaign=SomeCampaignString
We’ve also seen FeedBurner going crazy and making thousands of duplicate requests. One of the sites we host has gotten 45,000 simple status requests (HTTP “HEAD” requests) from FeedBurner today, for no good reason that we can see.
Read the rest of this entry »
Many Web sites write data to a database. Usually, the data absolutely must be properly saved, so the default way of adding records (using an SQL “INSERT” statement) ensures that the data is permanently stored on the server’s disks. Doing that takes a relatively long time in computer terms — it’s much slower than most things computers do.
In some cases, you might be storing data that’s not quite so important. And if it means your application can run much faster, you might be willing to risk a very small chance of data loss. That’s where MySQL’s “INSERT DELAYED” statement, which works with MyISAM table types (but not InnoDB tables), can be useful. (Tables are created as type MyISAM by default, so most tables are eligible to benefit from this tip.)
Read the rest of this entry »
