what is the "dhcpd.leases" rotate period
dhcp1 at thehobsons.co.uk
Wed Sep 5 18:20:07 UTC 2007
Sébastien CRAMATTE wrote:
>What is the "dhcpd.leases" rotate period
>I've build a lease parser in perl and I've remarked that dhcpd.leases
>fille size still very small ... seems to be rotated ...
>Someone can give me some explanations ?
You mean the lease file rotation ? This has been
covered many times on this list, though I'm not
sure it's in the documentation.
The working database for the server is held in
memory, the file on disk is purely a backup plus
persistent storage across restarts. The file is
read during startup and then not read again, and
updates are added to the end - ie it is a log of
transactions. Lease record are NEVER updated in
the file, only new records added. To avoid
infinite growth, the server periodically cleans
up the file by :
1) Writing a new file from it's in memory database.
2) Renames the existing lease file.
3) Renames the new file to dhcpd.leases.
The period is fixed in the source code at 1 hour.
If you are writing a program that parses the
leases file, you need to be aware that each
iteration of the file will not contain any
history of events prior to the last rotation (ie
only the last state of any lease is held). If you
are trying to extract a record of transactions
then it may be more accurate to parse the backup
file after each rotation rather than try to catch
updates that occur just before the file is
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