On 17Nov2014 13:22, Rick Stevens <ricks@xxxxxxxxxxxxxx> wrote:
On 11/17/2014 11:28 AM, jd1008 issued this missive:Man page says: ... fdatasync physically write output file data before finishing fsync likewise, but also write metadata There is no explanation about this, as dd is supposed to be agnostic about the type of the data. If a disk is being dd'ed out to a file and the disk is mounted, (which is a BAAAAD thing to do), then even there, dd is agnostic about FS data and FS metadata. So, what data and metadata is the manpage talking about?I believe it's referring to LVM or BIOS RAID metadata.
Not at all. dd neither knows nor cares about the underlying disc metaphor (RAID, whatever). These two terms refer to the fdatasync and fsync system calls; see "man 2 fdatasync" and "man 2 fsync". To quote from the fdatasync manual entry:
fdatasync() flushes all data buffers of a file to disk (before the system call returns). It resembles fsync() but is not required to update the metadata such as access time. and has some followon discussion. Cheers, Cameron Simpson <cs@xxxxxxxxxx> Never attribute to malice that which can be attributed to stupidity. - Hanlon's Razor -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
