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Andrew Pollock

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Sunday, 09 November 2008

Keeping hard drives cool

I've had this crazy ATA over Ethernet SAN for my MythTV setup for as long as I've been running MythTV. I'm using minotaur, an old Pentium III 1RU VA Linux server as the "head".

Originally, I had 4 IDE hard drives, attached to minotaur via IDE-USB adapters. This worked perfectly fine, but I missed the ability to query SMART information, and do other low-level drive tweaking with hddparm

So a while ago, NewEgg had a sale on 750Gb SATA drives, and I bought a 4 port eSATA card, and took the plunge with SATA. That all went fine.

The entire time, I've had the 4 hard drives themselves just sitting on top of minotaur, on cork trivets. The whole arrangement is in the bottom of our linen closet, as this is where the patch panel for the apartment is.

I've graphed the temperature of linen closet for some time now, but the benefit of having hard drives connected via SATA was that I could easily graph the temperature of them as well, which I started doing recently.

The catalyst for wanting to do this was that I had a drive fail, and I was concerned that they were getting too hot, just sitting in the closet with no airflow. Matt Bottrell's recent reminder of Google's research into hard drive failures also helped bring this concern to forefront.

Seagate's product documentation for the Barracuda 7200.10 claims that ambient operating temperature must be between 0°C and 60°C. I'm assuming that's the environment the hard drive is in, and not the temperature of the drive itself as reported by something like hddtemp. The closet is typically in the high 30's. If you believe what SMART reports, it seems to imply that anything over 45°C is a Bad Thingtm.

So after I had a drive fail, I figured I should probably try to do something about the temperature situation, and started looking around for an external enclosure.

I'd previously had problems with the IEC-to-Molex power supplies I was using to power the disks, and think that they'd been the cause of some failures of my IDE disks, so was quite eager to stop using them as well, which was something else an external enclosure would give me.

I had trouble finding an enclosure that presented 4 separate eSATA ports, and I was talking to Marc about SATA port multipliers, when he mentioned he had a brand-new unused full-height SCSI enclosure, for four disks, which was surplus to his requirements. Since all I really needed was external power and cooling, I thought I could cannibalise this to my needs.

Sure enough, I could just remove the SCSI cables and their Centronics connectors, and feed the eSATA cables out the gap they left, and use the molex-SATA power splitters I already had. Because the enclosure was intended for full-height 3.5" hard drives, there was plenty of air space between each disk. The enclosure included two fans.

The results? Well the graph speaks for itself:

Graph of hard drive temperatures

(I'm not entirely sure why minotaur's internal disk occasionally reports a very low temperature)

The added bonus is I've cleaned up the rats nest of cables in the linen closet. So thanks very much, Marc!

[14:22] [tech] [permalink]