Disk light blinking

The hard drive light blinks costantly. No recording, playback, or watching going on. Is this normal?

I can’t say if it is normal for your drive or not, but mine only blinks when something is going on, and does stay off when all functions on the Tablo are idle - and I suspect yours probably should work that way as well.

Have you rebooted the Tablo with the drive disconnected and tried reconnecting it?

Powered Tablo down. Disconnected drive. Powered Tablo up. Reconnected drive. Light blinked a couple times then went steady. After about a minute went back to constant blinking. I have only had the unit about a week and its done it since we got it. The drive is a WD Elements, 1 tb.

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My WD 2TB Elements Portable External Hard Drive LED activity light blinks every 2 seconds when nothing is going on, too.
I researched this, and found a WD article describing something similar when using a WD drive with MS Vista, which may apply here, too.
The computer, Tablo in this case, goes into a sleep mode, and keeps sending the hard drive a standby command even if the drive is already in its own sleep mode (a.k.a. spun down).
My drive is defintely spun down, and the blinking LED continues every 2 seconds.
Solid LED for 2 seconds, then 2 seconds of LED off, then solid LED for 2 seconds, …

Annoying, but normal.