Matt Simerson

Until recently, having a 3 year old laptop was unthinkably slow. Yet today I find myself with a mid-2010 MacBook Pro. Not long ago, RAM and processors leapt past the point of being good enough. My long-in-the-tooth laptop is sporting a 2.66 GHz Core i7 CPU, 8GB of RAM, and half TB of storage. All of those specs are sufficient for my needs.

The problem with my old system was the performance of the spinning disk. Its laggard ways had me lusting after a new Retina MBP with 512GB SSD. I would have leapt, but two things held me back: Anand’s advice, and my employer donating a Corsair CSSD-F240GB2 to me. Dropping in a SSD made a dramatic difference. Instead of drooling after a new laptop, I was like a satiated diner, admiring the dessert menu, but passing.

I was content, until my Mac started to hang once a week with identical symptoms each time. Apps that did not need disk I/O (terminal & IM sessions) would keep running while those in need of disk would hang interminably. The only solution is a hard power off. I looked into it and Corsair offers a firmware update, principally to address wake-from-sleep hangs on Windows. The firmware updater is  Windows only. It’s worth a try, right?

My first stab was connecting the SSD to another Mac running Windows 7 in VMware, via USB. The update utility didn’t see the drive. To follow the updater instructions and connect via a Windows 7 computer via SATA and AHCI enabled, I would have to install Windows 7 via Boot Camp. Installing Boot Camp is generally easy: run the Boot Camp Assistant, let it carve out some disk space for Windows, reboot to the Windows install DVD and install.

Except I had a few obstacles:

• I had replaced my DVD drive with the SSD.
• Boot Camp Assistant will only allow a USB drive install of Windows on newer machines that ship without a DVD drive.
• Boot Camp could not partition my disk because it could not move some files.

To get Windows installed, I had to wipe my spinning disk, clone my SSD back to it, replace the SSD with the DVD drive, boot onto the spinning disk, run Boot Camp to partition the disk, install Windows 7, replace the DVD drive with the SSD, tweak the registry to support AHCI on my SSD, and finally run the Corsair firmware update utility. Which still did not recognize my disk. My next SSD will not be made my Corsair. And it might be wrapped in a new rMBP.

 

I was setting up monitoring of mail queues with the nagios plugin check_mailq and found it didn’t work on cPanel servers. Google led me to a few shell scripts that used sudo to run exim -bpc. I didn’t like that option so I dove into check_mailq, expecting to make a few changes to the code. Instead, I discovered that for exim, the check_mailq plugin expects to parse the input of a queue listing. From there, the solution was straight forward.

Edit nagios/utils.pm and set $PATH_TO_MAILQ = “/usr/sbin/exiqgrep”;

Add the nagios user to the mailnull group in /etc/group.

Add this to nrpe.cfg:

command[check_mailq]=/usr/local/nagios/libexec/check_mailq -w 100 -c 500 -M exim

Restart nrpe, and it works perfectly.

Nolisting is a spam fighting technique that works by listing an unavailable MX as the highest priority (lowest MX value) mail server. The idea is that any proper mailer will detect the unavailable MX and automatically retry the next highest priority MX record.

On Feb 7th, 2012, I dedicated one of my IPs to the job of not listening for SMTP traffic, set up a host record, and then configured a few mail domains with my faux MX as the highest priority.

On March 5, I removed the faux MX records. Over the course of a month, the half dozen users of these mail domains had all experienced the loss of valid mail and noticed. Undoubtably, they lost more valid messages than they noticed.

Before I removed the faux MX records, I did some sniffing of the SMTP traffic hitting my faux MX. During observation, most of the failures I witnessed were being sent by an application written using JavaMail. Apparently it’s popular with banks (for sending account notifications), news organizations, and online photo processors.