Hi lvm folks, Recently We received a report about the device cache issue after vgchange —deltag. What confuses me is that lvm never calls fsync on block devices even at the end of commit phase.
IIRC, it’s common operations for userspace tools to call fsync/O_SYNC/O_DSYNC while writing critical data. Yes, lvm2 opens devices with O_DIRECT if they support , but O_DIRECT doesn't provide data was persistent to storage when write returns. The data can still be in the device cache, If power failure happens in the timing, such critical metadata/data like vg metadata could be lost. Is there any particular reason not to flush data cache at VG commit time? Thanks — Su
