Re: Problem with disk

[Ric Wheeler <ric@emc.com>]

Mark Hahn wrote:

>>I would suggest that you should run with the write cache disabled unless 
>>you can verify working barrier support.
>>    
>>
>
>this is true, but extremely conservative/paranoid.  it makes a lot 
>of sense if you're handling banking transactions or if you really
>see a lot of abrupt power-offs (yank the battery).  what are the chances
>of a drive failing to write dirty blocks when idle, halting?
>  
>
The write cache in modern drives is multiple megabytes - 8 or 16MB is 
not uncommon. The chances that you have data that is lost on a power 
failure in the write cache is actually quite high...

I agree that most people should not lose too much sleep over this.

>don't get me wrong: write barriers are A Good Thing.  just that Linux 
>survived very nicely for many years before such things were bothered with.
>
>  
>
>>The fact that your drive reports IO errors is also worrying - you might 
>>just have a bad drive...  You can look at drive help with tools like 
>>smartctl.
>>    
>>
>
>IO errors trump any concerns for write barriers - there's no need to 
>even think about barriers or cache settings if the disk is, for instance,
>reporting media errors...
>
>  
>
Agreed again ;-)

ric