>>>>> "Joe" == Joe Peterson <[EMAIL PROTECTED]> writes:
Joe> You don't mention what I believe is the *key* issue (and I don't Joe> think the author did either, but I skimmed his article): data Joe> integrity. I'm not talking about blatant failures or known need Joe> for an fsck, but rather silent corruption. We're very concerned about data integrity. With btrfs everything is checksummed at the logical level. This allows you to detect data corruption, repair bad blocks using redundant, good copies, perform data scrubbing, etc. A related, but orthogonal data integrity measure is the T10 DIF infrastructure that I am working on. DIF enables protection at the sector level and includes stuff like a data checksum and a locality check which ensures that the sector ends up the right place on disk. If there is a mismatch the I/O will be reject by either the HBA or the storage device. That allows us to catch a lot of the corruption scenarios where we accidentally write bad stuff to disk. Right now the DIF checksum is added at the block layer level. Work is in progress to move it up into the filesystems and from there into user space. Eventually we'd like to be able to generate the checksum in the application and pass it along the I/O path all the way out to the physical disk. -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
