After having been frustrated for 2 weeks about the performance of my new raid-array, and spending an evening trying to pinpoint the issue, something that hasn’t happened to me in the 20 years I’ve been working with computers occurred. The magic smoke of a device was released upon connecting it.
I had pinpointed the performance-issue to a single disk in the array, which was acting weird. It would be detected as 500GB a single time, and as 1500GB the next. It’s read performance on sequential reads would fluctuate between ~80MB/sec (as the other disks) and < 1M/sec. Sometimes sticking at the snail-pace for minutes before going back to 80M/sec. After removing the disk from the array and trying it on a different controller it worked again for a while, but I cheered too soon, as the performance dropped again after a few minutes. I finally decided to connect the disk to a second machine, so I could run a long performance-test on it without impacting my normal use on the system it came from. So I plugged in the SATA and power-cables, turned the 2nd computer on, and was greeted by a sizable puff of gray smoke coming from the PCB of the drive. A nasty smell accompanied the smoke and signaled that this troublesome disk had spinned it's last cycles. There is no directly visible damage or burns, as the smoke came from the side of the PCB that's facing the disk, the smell probably largely coming from the foam that separates the disk housing and the PCB. Naturally the disk was no longer recognized by any system from this point forward... so I have to run back to the store (again) tomorrow to replace the disk (the 2nd in the batch of 4 I bought 2 weeks ago). Oh well.... let's just hope this is the first and last time this happens ;P