Posts Tagged ‘memory’

Free Computer Burn-In Software

Tuesday, June 2nd, 2009

I thought that free burn-in software would be easier to find.

Every now and then I cobble a computer together from parts, or I have to diagnose a PC that is crashing from time to time.  Unfortunately, even though a PC can boot, it doesn’t mean that it’s stable and ready to go. The tool for this job is burn-in software.

I used to use the free-as-in-beer version of SiSoft Sandra, but over the years it has gotten rather bloated.  Anyway, SiSoft Sandra is more geared towards benchmarking a computer rather than stress testing.

Today, I found a great little tool that seems to do a good-enough job of testing the CPU and RAM – it also puts a modest amount of load on the hard drive.

The free tool that I am currently recommending: CPU Stability Test by Jouni Vuorio. It seems to run fine in all current versions of Microsoft Windows.

Link: http://www.pcworld.com/downloads/file/fid,7146-order,1/reviews.html

It’s a bit old, circa 2000, and I can’t find a current website for it… but it works.  There are several “high-quality”, i.e. non-spammy, websites that host CPU Stability Test. Just Google for it if the link above goes stale.

There is still room to find a better free utility, but for now I’m satisfied.  But, if you have other suggestions for free burn-in testing software, please leave a comment!

Update: A free utility for testing memory (i.e. looking for bad memory sticks) that runs inside Windows – http://hcidesign.com/memtest/. If you’ve got the ability to reboot the machine, then use Memtest86.

Reducing Memory Used by Milter-Greylist

Monday, July 21st, 2008

Our VPS was running low on free memory the last few weeks.  After a bit of research, we realized that our email greylisting software, Milter-Greylist was using the most memory of everything installed on our server.  More than our database engine, web server, email server, and everything else (not combined)!

For those who don’t know, Grey Listing delays emails in an attempt to foil spammers which don’t typically follow standards for retrying email messages. Milter-greylist is a package that works with sendmail, our SMTP server. Milter-greylist is great, however, it keeps it’s working history in memory, which was OK for the two years that we have run it.  However, the amount of spam attempts continues to rise… why don’t home users notice that their computers have become SPAM zombies anyway?

So, the milter-greylist was storing tens of thousands of records in memory.  It had to be reduced.  Rather than switch to a database driven greylisting package, we decided to start blocking some SPAM attempts earlier in the process.

We enabled the outright blocking of inbound email attempts by any IP address listed on Spamhaus.org’s SBL+XBL list.  SBL+XBL are lists of computers (built by crazy wizardry) that one can use to blacklist email attempts.  I’m uncomfortable using blacklists like this, but, what can you do?  The odds of good mail being lost are very small, and hopefully, anyone who happens to get bounced unintentionally can phone us.

So, following the simple instructions here:

http://www.joeldare.com/papers/spamhaus.pdf

We were able to reduce the traffic to Milter-Greylist and it’s memory usage by 2/3 to 3/4!  Uptime and performance of our VPS and therefore everything hosted on it should be slightly better.

Spammers suck.