On Fri, Feb 27, 2015 at 09:01:10AM +0100, Michael Kerrisk (man-pages) wrote: > On 02/27/2015 01:04 AM, Theodore Ts'o wrote: > > On Thu, Feb 26, 2015 at 02:36:33PM +0100, Michael Kerrisk (man-pages) wrote: > >> > >> The disadvantage of MS_STRICTATIME | MS_LAZYTIME is that > >> in the case of a system crash, the atime and mtime fields > >> on disk might be out of date by at most 24 hours. > > > > I'd change to "The disadvantage of MS_LAZYTIME is that..." and > > perhaps move that so it's clear it applies to any use of MS_LAZYTIME > > has this as a downside. > > > > Does that make sense? > > Thanks, Ted. Got it. So, now we have: > > MS_LAZYTIME (since Linux 3.20) > Reduce on-disk updates of inode timestamps (atime, > mtime, ctime) by maintaining these changes only in mem‐ > ory. The on-disk timestamps are updated only when: > > (a) the inode needs to be updated for some change unre‐ > lated to file timestamps; > > (b) the application employs fsync(2), syncfs(2), or > sync(2); > > (c) an undeleted inode is evicted from memory; or > > (d) more than 24 hours have passed since the inode was > written to disk. > > This mount significantly reduces writes needed to update "This mount option"? > the inode's timestamps, especially mtime and atime. > However, in the event of a system crash, the atime and > mtime fields on disk might be out of date by up to 24 > hours. > > Examples of workloads where this option could be of sig‐ > nificant benefit include frequent random writes to pre‐ > allocated files, as well as cases where the MS_STRICTA‐ > TIME mount option is also enabled. (The advantage of > (MS_STRICTATIME | MS_LAZYTIME) is that stat(2) will > return the correctly updated atime, but the atime > updates will be flushed to disk only when (1) the inode > needs to be updated for filesystem / data consistency > reasons or (2) the inode is pushed out of memory, or (3) > the filesystem is unmounted.) Is it necessary to repeat the reasons for flushing, which are stated above? > > Cheers, > > Michael > > > -- > Michael Kerrisk > Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ > Linux/UNIX System Programming Training: http://man7.org/training/ > > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs Thanks! -- Omar _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
