Minimum hard drive operating temperature?

Hi, I have my unraid server sitting in my unfinished basement. The basement has two tiny windows that open to the outside and these windows are permanently open. Therefore the basement is always colder or hotter than the rest of the house.

During the summer, I had all the fans blasting at full speed and the hard drives were pretty cool (highest temp was around 29 degrees celsius)

Now that the winter is here, I turned down all the fans to low and the drives are down to 16-20 degrees. The temperature outside is about 5. My basement is probably around 10-15. How much lower do you think they can go while still being relatively safe? Where I live we don't get crazy low temperatures, so I don't expect it to go much lower, but I'd rather be safe

Thanks

Seagate has spec'ed their hard drives as having a minimum operating temperature of 0C.  As an aside, their spec for maximum operating temperature (case) is 60C!  (I believe most of us would be most uncomfortable if we had a drive with an operating temperature anywhere north of 40C!)

I would actually be quite concerned having a computer of mine in an unheated space because of humidity problems.  (I live in the northern part of the USA and most years outside temperatures can range from -17C to 38C with the relative humidity in the 70% to 90% range at some point during the day.)  Plus, basements in our area tend to have much higher humidity than than the outside environment. 

One problem with low temperatures is getting the hard drive to spin up to speed before the operating system time-out period has expired--- mainly because of 'stiff' lubricants.  I know that this was once a problem I had with an older  drive about fifteen years ago.

Google did a large study of HDD failure rates here:

http://static.googleusercontent.com/external_content/untrusted_dlcp/research.google.com/en/us/archive/disk_failures.pdf

There is a drive temperature vs failure rate chart on page 6, seen below.  Drive reliability was best in the upper 30C's with the failure rates increasing dramitically below 25C.

You are going to have more problems then just temperature. you will  have condensation from the temperature differences.

You will end up shorting something out from the moisture.

I have received many drives in the dead of winter in the mail. they are frozen when I get them. when they thaw you can see moisture forming on them.

another problem is rapid change of hard drive temperatures while operating can cause data loss (or so I have heard) the tracks get slightly out of alignment from rapid expansion. (urban myth or not? not sure)

You might consider covering up those windows in the winter?

if you must leave it as-is... I'd consider leaving the drives always spinning. it will help keep them at a (somewhat) constant temp

I am sure you're not alone in this situation. is it actually a basement or is it a crawlspace?

thanks for the replies.

It is actually a basement, however you need to climb down a ladder. But it's big and the ceiling is 7 feet tall.

The two windows are on either side, they are grated and about 6inx12inches in size

The temperature fluctuation is not that great. It is still semi insulated due to openings being really small and not allowing too much airflow. Plus, during winter, the house loses some heat through the floors into the basement.

I honestly don't expect it to get below freezing temperatures during winter. (Although I guess it is possible if it were to get really really cold outside)

I also checked the hardware for condensation or moisture (even early morning), it seemed dry and the basement doesn't feel any more humid than inside the house.

I changed the spin-down delay to "never" and will keep monitoring temps

Thanks