sync delay and consitency

Uwe Doering gemini at
Thu Nov 27 14:18:42 PST 2003

Ion-Mihai Tetcu wrote:
> I have a machine that randomly crashes. I wonder if lowering 
> Variable         Default      Description
> kern.filedelay   30           time to delay syncing files
> kern.dirdelay    29           time to delay syncing directories
> kern.metadelay   28           time to delay syncing metadata
> would help having a more up-to-date fs (using soft-updates). 

You can reduce these settings in order to narrow the window which you 
would lose data in if the system crashed.  However, it is important that 
you keep the numerical order of these variables.

> Also is there a reason for the 30-29-28 (the 1 differece between)
> sequence ?

It gives a FS w/soft-updates its crash resilience, by ensuring the order 
of disk updates for these three data types.  Meta data first, then 
directory data, and finally the actual file contents.

Uwe Doering         |  EscapeBox - Managed On-Demand UNIX Servers
gemini at  |

More information about the freebsd-questions mailing list