Archive
Posts from 2006
Getting ESX server to recognize Clariion devices
While setting up two new ESX 3.0 server nodes, I ran into a bizarre problem where the VI client refused to initialize several Clariion CX700 devices. Since the VI client isn't the best environment to debug problems, I ssh'ed into the service console, and began my research by running esxcfg-vmhbadevs to list the devices on the system: This listed the correct number of devices, so I decided to use dd to read data from one of the devices that was causing problems: Dd worked fine, but I was still unable to create a file system with the VI client or vmkfstools: To get a better idea of the disk device layout. I decided to run fdisk to list the label type and layout of each device: Hmmm -- each Clariion device contained an SMI label, and I started to wonder if this was causing the problem. To test my hypothesis, I used the fdisk utility to write a DOS label to one of the problematic devices: Once I labeled the device with a DOS label, vmkfstools and the VI client allowed me to initialize and use the device…
$ read more →Locating the services that will start when Windows boots
My Dell C400 runs Windows XP, and it was taking 5 - 10 minutes to boot. This wasn't always the case, so I started poking around to see which services where being enabled during startup. Windows maintains two registry keys for startup items, as well as the old trusty "Startup" folder in the start menu. Here are the keys you can check to see which services will start when Windows XP initializes: Registry key #1 HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run Registry key #2 HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run My problem turned out to be with VMWare server, and removing it made my machine boot quickly again…
$ read more →ZFS best practices and tuning links
I found a couple of interesting ZFS links this week: ZFS best practices: ZFS tuning:
$ read more →Buffering Apache logfiles with the BufferedLogs directive
On busy web servers, the process of writing to the access_log can sometimes overwhelm the spindles in a server. In Apache 2.0.41, the developers added the experimental "BufferedLogs" directive to buffer access_log entries in memory, and write them out as a single group. The documentation indicates that setting "BufferedLogs" to "On" enables buffered logging, but I couldn't find anything that described how to configure the size of the buffer. After a bit of poking around in mod_log_config.c, I noticed that the size of the buffer was controlled by the LOG_BUFSIZE macro: To see what LOG_BUFSIZE was set to, I searched for the value in mod_log_config.c…
$ read more →Generating core files from gdb
While debugging a problem a few weeks back, I needed to generate a core file from a hung process. I typically use the gcore utility to generate core files from running processes, but in this case I was already attached to the process with gdb, so gcore failed: Gak! I remembered reading about a gdb option that would dump core, so I wandered off to read through my gdb notes. Sure enough, gdb has a "generate-core-file" command to create a core file: Nifty…
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