Is there any sort of checksumming layer that could lie between the disk and ext3, or be implemented as part of ext3/4? We've just had a couple of drives recently where the drive started silently corrupting the data without generating any I/O or SMART errors. This is pretty disastrous as you don't necessarily find out about the corruption until it is too late. I imagine the overhead of such a layer wouldn't be that much. I would pay a few percent performance for knowing that the data is not corrupt. Jeremy -- Jeremy Sanders <jss at ast.cam.ac.uk> http://www-xray.ast.cam.ac.uk/~jss/ X-Ray Group, Institute of Astronomy, University of Cambridge, UK. Public Key Server PGP Key ID: E1AAE053
On Fri, January 11, 2008 12:54, Jeremy Sanders wrote:> Is there any sort of checksumming layer that could lie between the disk > and ext3, or be implemented as part of ext3/4?http://www.bullopensource.org/ext4/files/ext4.txt notes: * journal checksumming for robustness, performance (prototype exists) Features like metadata checksumming have been discussed and planned for a bit but no patches exist yet so I'm not sure they're in the near-term roadmap. ...but apart from that, only ZFS comes to mind: http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#Checksums C. -- make bzImage, not war
Hi, You could use tripwire to check periodically all files instead of relay on the file system for that task. (I think no file system does this checking by now) Jordi Jeremy Sanders wrote:> Is there any sort of checksumming layer that could lie between the disk and > ext3, or be implemented as part of ext3/4? > > We've just had a couple of drives recently where the drive started silently > corrupting the data without generating any I/O or SMART errors. This is > pretty disastrous as you don't necessarily find out about the corruption > until it is too late. > > I imagine the overhead of such a layer wouldn't be that much. I would pay a > few percent performance for knowing that the data is not corrupt. > > Jeremy > >-- ...................................................................... __ / / Jordi Prats C E / S / C A Dept. de Sistemes /_/ Centre de Supercomputaci? de Catalunya Gran Capit?, 2-4 (Edifici Nexus) ? 08034 Barcelona T. 93 205 6464 ? F. 93 205 6979 ? jprats at cesca.es ......................................................................