[lkml]   [2009]   [Sep]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [testcase] test your fs/storage stack (was Re: [patch] ext2/3: document conditions when reliable operation is possible)

>>> people aren't objecting to better documentation, they are objecting to
>>> misleading documentation.
>> Actually Ric is. He's trying hard to make RAID5 look better than it
>> really is.
> I object to misleading and dangerous documentation that you have
> proposed. I spend a lot of time working in data integrity, talking and
> writing about it so I care deeply that we don't misinform people.

Yes, truth is dangerous. To vendors selling crap products.

> In this thread, I put out a draft that is accurate several times and you
> have failed to respond to it.

Accurate as in 'has 0 information content' :-(.

> The big picture that you don't agree with is:
> (1) RAID (specifically MD RAID) will dramatically improve data integrity
> for real users. This is not a statement of opinion, this is a statement
> of fact that has been shown to be true in large scale deployments with
> commodity hardware.

It is also completely irrelevant.

> (2) RAID5 protects you against a single failure and your test case
> purposely injects a double failure.

Most people would be surprised that press of reset button is 'failure'
in this context.

> (4) Data loss occurs in non-journalling file systems and journalling
> file systems when you suffer double failures or hot unplug storage,
> especially inexpensive FLASH parts.

It does not happen on inexpensive DISK parts, so people do not expect
that and it is worth pointing out.

(cesky, pictures)

 \ /
  Last update: 2009-09-02 22:15    [W:0.185 / U:44.368 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site