Last time I said that you can set a starting value for the USL’s coefficient of performance and let your modeling software (R, gnuplot, etc) manipulate this as part of the regression to find the best fit. However, there is a subtlety in the USL model that you need to be aware of. Here is a picture of the low-end of the curve:
I recently wanted to add two individuals to my list of professional contacts at LinkedIn. I was extremely disappointed at the modified user interface (UI) experience that made it difficult to do so. In the past, you just entered a list of emails.
Many companies these days pressure you into opening up your entire network of contacts for their benefits of knowing your social graph. This is unacceptable.
You have to go thru the following complexity just to send an email request for connection in LinkedIn now.
Last time I said that the USL has a forgotten third coefficient, the coefficient of performance. This is the same thing as the system’s throughput at concurrency=1, or C(1). How do you determine this coefficient? There are at least three ways.
I prefer to run MySQL with innodb_flush_method=O_DIRECT in most cases – it makes sure there is no overhead of double buffering and I can save the limited amount of file system cache I would normally have on database server for those things which need to be cached – system files, binary log, FRM files, MySQL MyISAM system tables etc.
pt-stalk recipes: Gather forensic data about MySQL when a server problem occurs
It happens to us all from time to time: a server issue arises that leaves you scratching your head. That’s when Percona Toolkit’s pt-stalk comes into play, helping you diagnose the problem by capturing diagnostic data that helps you pinpoint what’s causing the havoc hitting your database.
MySQL MHA by Oracle ACE Director Yoshinori Matsunobu is an excellent open source tool to help in providing HA with native MySQL replication. The installation however is dependent on some Perl packages and to the untrained eye this may be an issue if you are using Percona Server as your choice of MySQL implementation.