lkml.org 
[lkml]   [2001]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] 64 bit scsi read/write
At 4:04 PM -0600 2001-07-13, Andreas Dilger wrote:
>**) As I said in my previous posting, it depends on if/how MD RAID does
> write ordering of I/O to the data sector and the parity sector. If
> it holds back the parity write until the data I/O(s) are complete, and
> trusts the data over parity on recovery, you should be OK unless you
> have multiple failures (i.e. bad disk + crash). If it doesn't do this
> ordering, or trusts parity over data, then you are F***ed (I doubt it
> would have this problem).

That wouldn't help, would it, if >1 data sectors were being written.

The fault mode of a sector simply not being written seems like a real
weak point of both RAID-1 and RAID-5. Not that RAID-5 parity ever
gets checked, I think, under normal circumstances, nor RAID-1 mirrors
get compared, but if they were check and there was an parity or
mirror-compare error and no other indication of a fault (eg CRC),
there's no way to recover correct data.
--
/Jonathan Lundell.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:57    [W:0.108 / U:0.460 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site