Re: [CentOS] Calling All FS Fanatics

[Les Mikesell <lesmikesell@xxxxxxxxx>]

On Thu, 2006-10-05 at 12:33 -0500, Steve Bergman wrote:

> > Yea, I'm sure. With write-caching turned off on the 3Ware controller only and
> > writing to an XFS filesystem:
> > 
> 
> You might look into the work done on "write barriers" in more recent
> kernels.  They are supposed to obviate the need to turn off write
> caching.  However, I'm not certain how they relate to hardware raid.
> The kernel needs to be able to issue a cache flush command to the
> drives, which makes it a controller driver issue.  Anyone have any more
> info on this?

I thought that journalled file systems only had to count on the
disk/raid not re-ordering the writes to avoid filesystem corruption.
That is, is doesn't matter if the writes are cached as long as what
is written is written in the same order as the OS issued the writes.
You just lose the data of anything that did not make it to the disk
but you shouldn't mess up the relationship between free/allocated
space and the inodes using it.  Is that impression incorrect?

-- 
  Les Mikesell
   lesmikesell@xxxxxxxxx


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