On 2/21/07, Kai Ponte <[EMAIL PROTECTED]> wrote:
On Wednesday 21 February 2007 06:42:19 am Joachim Schrod wrote:
> Joachim Schrod wrote:
> > David Brodbeck wrote:
> > At one of my customers, 10,000s of disks are in use at the servers.
> > There MTBF numbers are reliable indicators of how much disks one has to
> > buy in advance to exchange the defect ones.
>
> For the record, I should add that one needs to collect MTBF numbers
> (actually, MTTF and MTTR numbers) onself. Data from other
> organizations is not reliable, the variance seems to be quite high.
>
> Therefore, this may be only of use for large installations, and not
> for SOHO or mid-sized environments that are probably most common on
> this mailing list.
Joachim has a valid point.
Though this may be off-topic, I felt it important to state:
In our data center, we have 4 EVA 5000 machines each with 168 physical drives.
The drives range in size from 72GB to 300GB. We use MTBF in order to
calculate our drive replacement costs for these machines. So far we're only
replacing about one drive per month. The oldest EVA is roughly five years
old.
Now, the data center is climate controlled and entirely supplied by redundant
UPS units. In addition we have a diesel generator for backup. The generator
gets tested at least twice a year to ensure it kicks in. IOTW, the power
never goes off and the temperature does not go above 65f/18c.
--
kai
RE: The other thread that talks about SATA & SCSI being the same quality.
I have not read all of the referenced docs, but I did read the Google
paper that talks about consumer grade PATA / SATA drives.
It clearly shows a 9% failure rate starting in the 3rd year under
conditions similar to what Kai describes above.
Kai describes having over 600 drives operational for different time
frames, but only having 12 or so failures a year. ie. about 2%
Its fairly anecdotal and maybe most of Kai's drives are 2 years or
less old, but it does not sound that way.
All I can say if I was buying drives for a data center I would much
rather buy the drives Kai has than I would the ones Google has been
using.
Disclosure: I'm HP Certified to provide sales support on the EVA-5000.
Greg
--
Greg Freemyer
The Norcross Group
Forensics for the 21st Century
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