Feb 27

Homemade Bench top Power Supply

By jason Linux/Unix Oprating system No Comments »

I’ve always had an interest for electronics and recently I’ve been exploring my interests more. Last week I sorted through my tub of parts and placed them in individual draws. It took a good while to sort everything but I think it was worth it. I’ve seen power supplies built from PC power supplies before so I thought I’d build one my self. Thing is, I never really got around to it.

Yesterday I was feeling rather ambitious and decided to make a bench top power supply for small electronics. All the sites I found I have lost, so I kind of made it up as I went along. Most of them used ATX power supplies that are readily available, but I opted for the easy way out and used an AT with a hard on/off switch. At first this was the only reason I used it, but there are more advantages to using a AT over an ATX power supply for an external power supply. Firstly, it was cheap, well free actually. I took it from a PC that I had modified some time ago. I have a box full of AT power supplies in storage that I’ll get to some time and replace it. But I won’t be using the PC it came out of for a while, mostly because I have toaster ovens that are faster. Another reason it is better than a ATX is it has less voltages. The only voltages listed are 12v, 5v, -5v (7v) and GND. They vary in amps but are sufficient for what I will be using it for. It made it easy not to screw it up since there wasn’t many wires.

To make it was really easy. I took the top off. Drilled 4 holes in the case and inserted the insulated terminal, checking to make sure they didn’t ground out on the case. Cut most of the cables, leaving a couple of molex’s hanging out just in case I need them. I then soldered the remaining wires to a terminal by voltage (Yellow +12, Red +5, Red +/-5, Black GND.) It might not be the prettiest of them all, but I think it will do its job well.

Tagged with: • •
Aug 01

Improving Hardware to Speed Up the Mysql Server

By jason Mysql Server 1 Comment »

Hardware is one of the easiest improvements (if you have the cash) you can make to a poorly performing database server. As a general rule of thumb, pack in as much memory as you can first, then use the fastest disks you can get, and finally get the fastest CPU (Central Processing Unit). The best is to benchmark your system, using the various tools available to your operating system to see whether it’s the CPU, memory, disk speed, or a combination that is the bottleneck. This will give you the best idea of the vagaries of your usage and assist you in upgrading. Running the benchmark suite  will also help show the performance of different kinds of tasks.

Memory

Memory is the most important element because it allows you to tweak the mysqld variables. Large amounts of memory mean you can create large key and table caches. Memory that is as large as possible allows MySQL to use quicker memory rather than disk as much as possible, and the quicker the memory is, the faster MySQL can access the data stored there. Large amounts of memory on its own is not as useful as if you actively tweaked the mysqld variables to make use of the extra memory, so you can’t be too lazy and just stick in the memory and wait for fireworks.

Disks

Ultimately, MySQL has to fetch the data from disk, and this is where fast disk access plays a role. The disk seek time is important because it determines how fast the physical disk can move to get to the data it needs, so you should choose the disk with the best disk seek time. Also, SCSI (small computer system interface) disks are usually faster than IDE (Intelligent [or Integrated] Drive Electronics) disks, so you’ll probably want these.

An important improvement you can make is to stripe data across multiple disks (where the OS breaks data in parts, spreading it evenly over multiple disks), as well as symlinking (where you create a link from the data directory to another disk). InnoDB tables have a mechanism to split data across multiple disks quite easily, but MyISAM tables do not (being made up of single files), so striping or other forms of RAID can be quite useful. "Multiple Drives," looks at these topics in more detail.

CPU

The faster the processor, the quicker any calculations can be done and the quicker the results sent back to the client. Besides processor speed, the bus speed and the size of the cache are important. An analysis of available processors is beyond the scope of this book and will probably be outdated before this book is even published, but be sure to investigate your processor possibilities carefully to see how it performs in various

Tagged with: • • •
preload preload preload