[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] Re: Notes on block I/O data integrity
From: |
Jamie Lokier |
Subject: |
Re: [Qemu-devel] Re: Notes on block I/O data integrity |
Date: |
Wed, 26 Aug 2009 19:57:55 +0100 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Christoph Hellwig wrote:
> > what about LVM? iv'e read somewhere that it used to just eat barriers
> > used by XFS, making it less safe than simple partitions.
>
> Oh, any additional layers open another by cans of worms. On Linux until
> very recently using LVM or software raid means only disabled
> write caches are safe.
I believe that's still true except if there's more than one backing
drive, so software RAID still isn't safe. Did that change?
But even with barriers, software RAID may have a consistency problem
if one stripe is updated and the system fails before the matching
parity stripe is updated.
I've been told that some hardware RAID implementations implement a
kind of journalling to deal with this, but Linux software RAID does not.
-- Jamie
[Qemu-devel] Re: Notes on block I/O data integrity, Nikola Ciprich, 2009/08/25
[Qemu-devel] Re: Notes on block I/O data integrity, Rusty Russell, 2009/08/27
Re: [Qemu-devel] Notes on block I/O data integrity, Jamie Lokier, 2009/08/27