Archive for the ‘Linux’ Category

Delphi, Firebird, IBObjects and Transaction Management

Thursday, November 17th, 2011

I recently had reason to revisit transaction management in our application.  The application makes extensive use of data aware grids (TDBGrid) and, as I am sure everyone is aware, it is impossible to explicitly manage transactions when you are displaying data in a grid.

Fortunately, IBObjects provides the means to automatically clean up transactions left hanging by TDBGrid.  Unfortunately, this isn’t as well documented or as straightforward as I would like.  So, after much research using the programmer’s secret weapon (Google) and a few questions posted to the IBObjects support group (thanks Jason) I think I finally understand how it works. (more…)

I/O Errors Reported for USB Disk Drives After Inactivity

Monday, June 22nd, 2009

I just purchased a new USB disk to use for backups on my Linux server.  The old one had died so I got one of the new Seagate terabyte units.  Everything seemed find until the disk had been inactive long enough for the firmware to put the disk into power saving mode and spin it down.  The first attempt to access the disk after that resulted in Linux reporting an I/O error.

I found a simple way to get around this problem.  Before accessing the disk simply issue the following command:

 sdparm –command start <device>

where <device> is the device name for your USB drive.  In my case, /dev/sdc.

Since I only use the disk for backups and all of my backups are run from shell scripts this works very well for me.  Someone who is using a USB disk in a more adhoc fashion will probably have to set the disk’s timeout value such that it never goes inactive and spins down.  You can use the sdparm command for that as well but the setting names and values probably vary from disk to disk so it isn’t really possible to give complete details here.

Minimalist Linux Distro - Networking - Part II

Friday, December 19th, 2008

Well, I finally got my 16-bit wireless card, a Netgear MA401.  I plugged it into the laptap and prepared myself for a struggle to get in configured and running.  I needn’t have worried.  Linux detected and configured the card at boot time.  No problems at all.  Very nice.  Next I needed to set the encryption keys and so forth.  This was bit more of a challenge but only because the configuration utility (WLAN setup tool from the control panel) used slightly different terminology that I was used to from the Windows world.  The whole setup from start to finish took less than 10 minutes.  Sweet!

Minimalist Linux Distro - Using a Digital Camera

Wednesday, December 10th, 2008

Once I got the basic operating system working it was time to see if I could use this for the intended purpose, that is, dumping photos from my digital camera and previewing them.  A minimum of poking around resulted in success.

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Minimalist Linux Distro - Networking

Wednesday, December 10th, 2008

Once I got Damn Small Linux installed to my laptop I needed to get the network working.  I decided to use the DWL-650 wireless adapter that I was using for another laptop since it was readily available and it was listed as one of the adapters that worked with DSL “out of the box”.  So, I plugged it in and guess what?  It didn’t work.  Oh Joy!

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Minimalist Linux Distro

Wednesday, December 10th, 2008

I recently had a need (OK not so much a need as a desire) to breath some life back into an old laptop.  I wanted to have an ultra cheap laptop that I could lug around to preview photos from my digital camera, browse the web, check my email, etc.  I wanted something cheap enough that if it got trashed or stolen while travelling that I wouldn’t care.  Since I had an old 233 MHz MMX AMD with a 2GB hard drive and 64MB RAM that was gathering dust in a closet because it couldn’t run any version of Windows newer that Win98 I decided to see what could be done with it.

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Samba Performance Woes

Monday, July 23rd, 2007

I just spent a couple of frustrating days (are there any other kind?) troubleshooting a Samba performance problem on our new Linux server (kernel 2.6.21.5).  Network I/O between our XP machines and the server was SSLLOOWW!!  After much tearing of hair and gnashing of teeth, it turns out that the drivers for the onboard ethernet controller (Realtek 8168B 1GB ethernet) are buggy.  Some fairly exhaustive searches with Google failed to turn up any patches that were reported to work, so I disabled the onboard controller and stuck in an old 3Com 905B that I had in an old machine.  Presto, everything started to work just as it should.

Some fun we’re having.

Installing SCSI Tape for Slackware 10.0

Friday, July 6th, 2007

Well, I finally got around to installing the DDS-3 tape in my new linux server today. Since I had completely forgotten how I had done this last time I had to figure it out all over again. (more…)