An in-your-face lesson about power draw
On Tuesday I got my act together, wandered down to Dick Smith Electronics at North Sydney and purchased the internal drive power-splitter cable that I’d been meaning to get for weeks. This was all part of the grand plan to install another 2 SATA disks inside my Ultra20-M2… along with the 4 36Gb scsi disks I’ve got attached in a multipack.Great idea, but with insufficient regard for the limitations of my hardware.First off, the sata cables that I used were “standard” pc cables, so their plug length was about 2x the plug length that Sun uses when building these boxes. Not a problem on the motherboard end, but definitely a problem when you want to close the case if you don’t rotate your additional disks by 90 degrees.Secondly, current and power draw. The Ultra20 and Ultra20-M2 come with a 400W psu, which as far as I’m aware is plentiful enough to run the box with 2 disks and each PCI and PCI-Express slot filled, but not if you want to add extra disks. That’s what I hadn’t bothered to think about. My disk0 and disk1 are 320Gb Seagate ST3320620AS SATA disks which run just fine. The two disks I added were a a 200Gb Seagate ST3200822AS and a 300Gb Maxtor 6V300F0.Earlier this evening I noticed that a lot of processes were starting to hang – firefox, thunderbird, gaim, xchat … apache, postgres, tomcat …. and shortly thereafter everything decided to not respond. I was able to run a
reboot -dq though, so I got some data.On getting back to the grub screen, I received the worrying message that the system thought I had no slice 0 on my boot disk. Eeeeek! Power-off and power-on … boot up …. login …. hangHard hang. No chance of using F1+A to get out of this. Power-off it was.While I’d been waiting to see whether the hang was really hard I did a bit of thinking. What was the last change I made to the system? [added new disks internally] Was it disk-related? [yes] Am I an idiot? [quite possibly]Power-off, unscrew the case, remove the extra disks and re-set the original drive power cable, power-on, boot up with no problems whatsoever.I figure I’m now on the lookout for an appropriate hba with external connections along with an external enclosure to house the drives. Could be a while. In the meantime I think I’ve learnt my lesson.