# Intersting stuff on HD reliability



## TCM2007 (Dec 25, 2006)

http://216.239.37.132/papers/disk_failures.pdf

A bit academic perhaps, but interesting nonetheless. Debunks a few myths.


----------



## blindlemon (May 12, 2002)

> After their first reallocation, drives are over 14 times more likely to fail within 60 days than drives without reallocation counts


This clearly supports my theory that once you have had a sector error from a TiVo drive you should replace the drive ASAP.

Interesting that they didn't think temperature was a big factor though, although the temperature ranges they were monitoring tended to be lower than some of the hotter drives can get, probably due to them being mounted in well-cooled racks in Google's huge air-conditioned datacentre.


----------



## Blacque Jacque (Dec 26, 2006)

blindlemon said:


> This clearly supports my theory that once you have had a sector error from a TiVo drive you should replace the drive ASAP.


IME, once a drive develops a case of bad sector disease it'll usually go downhill rapidly. While not contagious it's somewhat virulent.


----------



## AMc (Mar 22, 2002)

I read an interesting article a while back about Google's hardware (reference lost in the ether)
Apparently they build their own servers from parts and by over specifying greater efficiency power supplies for they generate less heat and save money in operational costs on air conditioning. Because they take a holisitic approach to the total cost of ownership they take a different view from a hardware manufacturer who would want the cheapest unit with an acceptable mean time to failure.


----------



## iankb (Oct 9, 2000)

If you want a few facts/guesstimates about Google's hardware, see this page on Wikipedia.


----------



## Pete77 (Aug 1, 2006)

Interesting that a drive that doesn't fail in Year 3 then has a lower chance of failing in Years 4 or 5. This would certainly appear to suggest that not all drives are created equal.  

Also any drive on average only seems to have a 38% chance of failing in the first 5 years of life, which would rather explain the number of 6 year old Tivos still using their original drives. Especially given their other interesting conclusion that drives with much higher levels of utilisation do not actually seem to consistently experience a higher failure rate.

I'm also encouraged by their effective conclusion that absolute operating temperature is not a relevant factor in terms of reliability for hard drives operated anywhere within the normal manufacturer recommended safe temperature operating range. :up:


----------



## iankb (Oct 9, 2000)

I keep my PC drives healthy by keeping them at a reasonably-constant temperature (i.e. keeping the PC switched on), and regularly read-writing to all parts of the drive (by defragmentation and by using a security program to erase all unused space on the drive). According to my theory, this tends to keep the head and track alignment together by adjusting for any drift that may occur over time. It is also likely to detect faults before they get a chance to affect valuable data.


----------



## ericd121 (Dec 12, 2002)

AMc said:


> I read an interesting article a while back about Google's hardware (reference lost in the ether)
> Apparently they build their own servers from parts and by over specifying greater efficiency power supplies for they generate less heat and save money in operational costs on air conditioning. Because they take a holisitic approach to the total cost of ownership they take a different view from a hardware manufacturer who would want the cheapest unit with an acceptable mean time to failure.


I remember reading an article in either ITWeek or Computing mag, where someone from Google stated that hardware costs were almost academic; all they really care about is the energy cost, which is usually a lot greater than the purchase price of the kit.

Have I just said the same thing in different words?


----------



## Ian_m (Jan 9, 2001)

ericd121 said:


> I remember reading an article in either ITWeek or Computing mag, where someone from Google stated that hardware costs were almost academic; all they really care about is the energy cost, which is usually a lot greater than the purchase price of the kit.
> 
> Have I just said the same thing in different words?


It interesting this, I have just had a long discussion with a colleague say how can I trust my ADSL connection to a NetGear firewall router where as he uses an old P4 PC running Smoothwall to do all his firewall and routing. I measured my NetGear at 7W power his PC solution at 160W which works out £10/year and £232/year.

So what does he get for his £220 extra per year ??

I noticed he has recently bought a NetGear ADSL router......


----------



## SteveA (Oct 30, 2000)

Ian_m said:


> So what does he get for his £220 extra per year ??


Lots of carbon dioxide.


----------



## TCM2007 (Dec 25, 2006)

ericd121 said:


> I remember reading an article in either ITWeek or Computing mag, where someone from Google stated that hardware costs were almost academic; all they really care about is the energy cost, which is usually a lot greater than the purchase price of the kit.
> 
> Have I just said the same thing in different words?


Someone told me the other day that Google are relocating (have relocated?) much of their server farm to the mountains somewhere where they have their own hydoelectric power station, so large has their electricity costs become!

Plus they can have an underground bunker with force sheilds for when the evil Googlebots start to take over...


----------



## AMc (Mar 22, 2002)

SteveA said:


> Ian_m said:
> 
> 
> > So what does he get for his £220 extra per year ??
> ...


No, we all get to share that with him, how generous


----------



## mikerr (Jun 2, 2005)

Pete77 said:


> I'm also encouraged by their effective conclusion that absolute operating temperature is not a relevant factor in terms of reliability for hard drives operated anywhere within the normal manufacturer recommended safe temperature operating range. :up:


Google drives were probably well cooled, and the higgher failure rate for average cooler drives may have been due to spinup/down cycles (which they didn't record).

I'd be interested if anyone ever did a large survey of drives operating above 45C
as many poorly cooled drives in PCs and especially external drives run above that for their whole lives.

Some interesting failure rates by brand (translated from russian!)here


----------



## ericd121 (Dec 12, 2002)

Whilst we're in a geeky mood, how about a link to historical HDD prices?

From 1986, with price per Meg (in dollars), to 2006 with price per Gig, it makes for interesting reading. 

*http://www.mattscomputertrends.com/harddiskdata.html*


----------

