XFS syncs

[flux at hotbox.ru]

Hello Dave,

Thanks for the explanation and your suggestion to use wsync option.

On 07/04/2014 03:17 AM, Dave Chinner wrote:
> On Thu, Jul 03, 2014 at 10:05:53PM +0400, flux at hotbox.ru wrote:
>> Hi,
>>
>> I issue 'mkdir abc' on my xfs partition the cut off the power. After
>> reboot there's no 'abc' directoy.
>
> Because you didn't sync(1) the filesystem or fsync(2) the directory
> before you cut the power. Hence the change never hit the disk.
>
>> However, when I do that on ext4
>> the 'abc' direcory is always created after reboots.
>
> That'll be pure fluke - ext4 delays journal writes on namespace
> operations just like XFS does.
>
>> All the
>> settings, about mount options are default for my distro. What am I
>> missing or how do I change the things of the jounral or whatever?
>
> If you want directory operations to hitthe disk immediately, then
> mount with the "-o wsync" option. Be aware, however, that this will
> kill performance unless you have expensive storage with a large
> amount of battery backed write cache in front of the disks. There's
> a good chance it will also cause excessive wear on SSDs due to the
> frequent journal writes.
>
> Cheers,
>
> Dave.
>