Editing dhcpd.conf without corrupting leases

Simon Hobson dhcp1 at thehobsons.co.uk
Tue Apr 14 16:07:23 UTC 2009

Randall C Grimshaw wrote:

>Under the possibility that it might be buffers in his environment, 
>could a solution be as simple as issuing a 'sync' command before 

No. The disk buffers are transparent to applications - when you read 
a file, you will automatically be given data from the write cache for 
anything not yet committed to disk.

As I read it, the problem is that the application is terminated part 
way through writing out a record - so the bit that's missing never 
existed and so cannot be committed to disk with a sync call.

It would appear that the only way to fix this is to modify the 
program so that it will never quit part way through an update. Either 
by building up the record and writing it with one atomic call, or by 
deferring any quit instruction until the record is complete.

Simon Hobson

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