Author: Cody

I had a minor duh moment this week. For years I’ve worked on servers, big and small with SCSI disks. I’m familiar with SCSI technology and the quirks it has. In recent weeks I had purchased an ultra 320 SCSI hard disk for my linux workstation and an Adaptec 29160 card to drive it. I got the card used with a 68 pin SCSI cable complete with terminator.

I installed all the bits and mirrored my IDE disk onto the SCSI disk, rebooted and everything worked. Just to ensure there were no issues I was looking over my dmseg output and noticed the disk was running at 40mb/sec! I spent an hour going over jumpers and driver settings trying to figure out why this disk was running only at 40mb/sec. Then I actually looked at the cable connecting the two and realized that the cable was a plain old 68 pin Ultra SCSI cable. Doh!

For the curious, the way you can tell an Ultra 160 or 320 cable from a regular SCSI cable is the wires on a U160/320 cable are in twisted pairs. They use the same shielding idea as UTP ethernet cable to maintain speed at long cable lengths. Anyway, I’ve located some cheap U320 cables on ebay and they should be here any day now. Then I’ll be running at U160 from the disk to the SCSI card anyway. It won’t make a big difference since I’m only running the one disk on the SCSI bus and the data rate from the platters to the bus is only 60MB/sec.

Now if only I could get my DDS4 drive working with the 29160 card I’d be happy.

This morning our ipod mini suddenly stopped wanting to fast forward. To solve this I simply held down the select (center) button and the menu button together for 10 second. This causes the ipod to ‘reboot’ and after that the problem was solved. As a side note, clicking the select button while playing a song lets you fast forward and rewind with the scroll wheel, a definite plus when listening to hour long shows. Sometimes you just have to grit your teeth and read the manual. 😛

I got an Apple iMac on the weekend for cheap, the thing works except it’s cdrom won’t read discs properly. Since the cdrom in an iMac is slimline and integrated it’s not something you can swap out easily. Normally this wouldn’t be an issue but the system had no OS installed on it. I wanted a test OS X machine to test some backup software for work.

So I thought I’d just tear the thing apart and simply run a long ide cable outside the case to a normal cdrom drive and load OS X on it. No such luck, the slimline drive in the iMac has a strange compact IDE interface that doesn’t look compatible with either laptop ata or regular ata.

So I simply ran the primary IDE cable out of the case through the hole left by the extracted cdrom drive and put both the hard drive and the cdrom on the same ATA cable with the hard drive as master and the cdrom as slave. This worked fine except I couldn’t boot off the cdrom! I googled and found that the iMac will only boot off master devices.

So what did I do? Simple, I reversed the order! With the cdrom as master it let me boot off the OS X 10.3 cdrom, then I partitioned and installed the first stage of the OS X installer. When it came time to boot off the hard drive (after the first CD copies the base to the hard drive) I simply powered down, set the hard disk back to master and the CD as slave and voila! The install booted from the hard disk and continued on to disc 2 of the install. After the installer was all done and I was sure I didn’t need any more CD’s I shut down and re-assembled everything.

OS X 10.3.9 is not exactly screaming along on this machine but it’s fine for the script testing I have to do. Although I have to say, pink is not exactly my color.