[mythtv-users] Reassemble RAID with mdadm

Phillip Barnett phillip.p.barnett at gmail.com
Fri Mar 19 13:43:41 UTC 2010

I've got 320 disks in an Avid ISIS (not strictly RAID, but obscure  
algorithmic data spreading) array running 24/7, and lost about 3 in  
the past year, so about 1% a year.
Granted these disks are probably not consumer grade, but I put 4  
Maxtor disks in two Tivos in 2001, and they're still running, and  
actually recording every second of every day since.

Anecdata, eh!


Sent from my iPhone

On 19 Mar 2010, at 12:40, John Drescher <drescherjm at gmail.com> wrote:

>> On a modern CPU, there is a theoretical slowdown calculating  
>> parity, but
>> my quad core runs about 5% of one core when I'm thrashing the  
>> drives hard.
>> Frankly, any modern system has CPU to burn, and I don't believe  
>> parity
>> calcs are a real-life impact on performance.
> Agreed. Even on 5 year old systems the cput hits 7% max unless the you
> are rebuilding or reshaping then it can hit 25% on 1 core..
>> RAID5 is the most space/cost efficient.  You get n-1 space, so with  
>> a 5
>> drive array, you get 4 disks worth of space.
> Agreed again
>> I had a lot of problems with RAID5 and consumer grade disks.  My  
>> disks are
>> generally failing about 1 every 3-6 months, in a 6 disk array.   
>> Which makes
>> sense if you figure the life of a drive is 2-3 years.  My theory  
>> here is
>> that consumer grade drives are made to a budget.  They give a 3 year
>> warranty, but they're assuming you don't run it 24x7.
> There is something very strange here. I have 100+ such disks in raid
> and  I see 1 to 3 total failures per year running 24/7/365. And these
> are systems that I guarantee are used more than your Mythtv box.
> John
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