Re: Some very basic questions

[Ric Wheeler <rwheeler@redhat.com>]

Chris Mason wrote:
> On Wed, 2008-10-22 at 14:27 +0200, Stephan von Krawczynski wrote:
>   
>> On Tue, 21 Oct 2008 13:31:37 -0400
>> Ric Wheeler <ricwheeler@gmail.com> wrote:
>>
>>     
>>> [...]
>>> If you have remapped a big chunk of the sectors (say more than 10%), you 
>>> should grab the data off the disk asap and replace it. Worry less about 
>>> errors during read, writes indicate more serious errors.
>>>       
>> Ok, now for the bad news: money is invented.
>> If you replace a disk before real failure you won't get replacement from the
>> manufacturer. That may sound irrelevant to someone handling 5 disks, but is
>> significant if handling 500 or more. The replacement rate is indeed much
>> higher than people think from their home pcs.
>>     
>
> Hardware vendors already do replace disks based on policies defined by
> their own array hardware.  These are already predictive.
>
> -chris
>
>
>
>   
One key is not to replace the drives too early - you often can recover 
significant amounts of data from a drive that is on its last legs. This 
can be useful even in RAID rebuilds since with today's enormous drive 
capacities, you might hit a latent error during the rebuild on one of 
the presumed healthy drives.

Of course, if you don't have a spare drive in your configuration, this 
is not practical...

ric